6-Inch vs 8-Inch Wood Chipper: What Each Size Handles and Needs

The 6 inch vs 8 inch wood chipper choice comes down to two things: the thickest wood you feed and the power you can put behind the feed roller. An 8 inch machine takes wood a third thicker, and its maker asks for a bigger tractor, more weight and more care at every step. I read a chipper spec the way I read a sprayer sheet, opening and power first and the headline number last, and this page follows that habit. You get the real differences, the jobs each size fits and the point where a rental or a professional is the safer call.

6-Inch vs 8-Inch Wood Chipper: What Changes at Each Size

According to Woodland Mills, its 6 inch PTO chipper takes wood up to 6 inches and runs on a tractor with 20 to 50 PTO horsepower, while its 8 inch model takes wood up to 8 inches and asks for 35 to 100 or more. Both feed through a hydraulic roller that has its own pump, so neither one draws on the tractor’s hydraulics. The two models stand in for their classes, and the table shows the size of the step. If the rotor and feed roller are new to you, my answer to “how does a wood chipper work” explains the rotor, knives and feed.

Two inches look small on paper. The arithmetic is not small. A log cut across at 8 inches has about 78 percent more wood in the cut than one at 6 inches, because the area grows with the square of the diameter. The maker’s own figures follow that: the horsepower for full-diameter logs rises from over 40 to over 60, the minimum tractor from 20 to 35 horsepower, and the manual weight by 190 pounds.

On my land that arithmetic ends the argument early. The pruning wood from the apricot and plum rows is twigs and small branches, far below either opening, so for my own piles I never get to the 6 inch or the 8 inch class. I compare the next sizes down in my 3-inch vs 4-inch wood chipper page.

What the Inch Number Really Measures

The inch figure is a rating, and makers rate different things under the same words. Before you compare two machines, find out which opening the number belongs to and which wood it assumes.

Opening, Chute and Wood Type

Woodland Mills prints a 6 inch chipping diameter for its smaller model and a 6 by 8 inch infeed opening, so the opening and the diameter are two separate figures. Toro prints a hopper opening of 6 inches maximum in its manual for a trailer brush chipper. A 15 horsepower gas chipper manual lists a chipping capacity of 6 inches, or 150 mm. These are three different wordings for three machines, and none of them settles the question for the next machine.

Wood type moves the limit too. One Woodland Mills manual cuts its 4 inch limit by 1 inch for certain hardwoods, so a rating can assume softer or greener wood than the pile in front of you. Read the manual of the exact machine for the wood its figure assumes, and for the opening it names. I do that before I look at anything else. A chipper’s 6 inch rating is its maximum diameter, and it does not mean every 6 inch limb feeds at full speed.

Full Diameter Needs Power

The same maker’s page adds the number that matters most. Chipping full 6 inch logs at full infeed speed takes over 40 horsepower at the PTO, and full 8 inch logs take over 60. A tractor at the bottom of the maker’s range can still run the machine, but it will not pull the thickest wood at full speed.

Engine Power or Tractor PTO

A PTO is the power take-off shaft on the back of a tractor. It turns at a set speed, 540 revolutions per minute in the Woodland Mills manuals, and a chipper that uses it carries no engine of its own. The alternative is a gas engine on the chipper itself, and I set the two power sources side by side in my PTO vs gas wood chipper page. Each class has a different first question.

The 6 Inch Class

A 6 inch PTO wood chipper from Woodland Mills lists 20 to 50 PTO horsepower. The gas side is different.

A 15 horsepower, 420 cc gas chipper manual prints a 6 inch capacity, a centrifugal clutch and a 2 inch coupler hitch. Toro’s 22604 trailer chipper uses a 25 horsepower Kohler engine and a 6 inch hopper opening. Gas towables like these need no tractor, but they need a hitch, a vehicle to tow them and space to turn. I weigh that space before I weigh the engine. If your branches are much smaller, my electric vs gas wood chipper comparison explains what each power type can chip.

The 8 Inch Class

Woodland Mills’ 8 inch model runs from a tractor PTO, so the tractor is the first thing to check. The maker lists 35 to 100 or more PTO horsepower, and it adds that full 8 inch logs at full speed take over 60. I treat a PTO chipper as a tractor question before it is a chipper question: how big the tractor is, whether the driveline shield is intact and where the machine can turn around.

Weight, Size and Towing

Weight shows the step between classes more plainly than any other figure, and it decides where you can store the machine and what can move it. Read each figure with its basis, because makers print product weight, net weight and shipping weight under the same word.

• 6 inch PTO class: 710 lb, product weight in the Woodland Mills manual.
• 8 inch PTO class: 900 lb, product weight in the Woodland Mills manual.
• 15 horsepower gas towable, 6 inch: 255 kg (about 562 lb), weight in its manual.
• Toro 22604 trailer chipper, 6 inch hopper opening: 1056 lb, weight in its manual.

Towable machines add a hitch and a travel rule. Toro’s manual says not to tow faster than 45 mph. The DK2 6 inch assembly guide recommends 25 mph at most, and the label on the machine says the same. Two manuals, two different speeds, so the only speed that counts is the one printed on your machine.

Feed System and Why It Matters for Safety

Both Woodland Mills classes pull wood in with a hydraulic feed roller, and my page on the hydraulic feed wood chipper shows how that feed differs from a gravity hopper. A control arm sets the roller to forward, neutral or reverse, and the manual says reverse pushes branches back out toward the operator. That roller is why a 6 or 8 inch machine can take thick wood without a push from your hand, and it is also the reason the rules here are strict.

Workplace studies of large hand-fed chippers describe the same pattern again and again: the operator is caught in the feed mechanism and drawn toward the rotating knives (1).

A review of worker deaths by chipper found caught-in incidents among the main causes, and it found that the feed controls do not reliably let a trapped worker free themselves (2). Tree care case series list being caught or dragged into a woodchipper as one of the main fatal incident types (3). These cases come from crews and professional machines, and the roller does not know who is feeding it.

Yard shredder and chipper machines hurt operators too. A plastic surgery report describes severe self-inflicted hand injuries from them, most often in fall and spring (4). I read the manual twice before I stand at an infeed, and I never reach in.

Which Size Fits Which Job

Match the machine to the thickest wood you feed regularly, not to the thickest wood you have ever seen on the pile. A size that fits the pile on a normal day is the right size, and one storm is no reason to buy for the worst pile.

When Neither Size Is Needed

A homeowner chipper shredder covers twigs and small branches, and its maker rates it far below 6 inches. Wood thicker than that is a saw and firewood job, a mulch job for a smaller machine after you cut it down, or a job for a larger rental. On my own land the thickest orchard wood goes to the saw and I feed only the small wood, while my wood chipper vs chainsaw comparison explains which jobs suit each tool.

When the 6 Inch Class Fits

A 6 inch machine suits property owners who regularly clear limbs close to 6 inches and have either a tractor with 20 to 50 PTO horsepower available or a vehicle to tow a gas unit. It is the smaller step into crew-style machines, and it keeps the weight near 710 pounds in the maker’s PTO class.

When the 8 Inch Class Fits

The 8 inch class fits acreage with a tractor that delivers 35 to 100 or more PTO horsepower, the range the maker lists, and a steady supply of thick wood. Tractor engine horsepower is a different rating, so check the PTO figure. Full 8 inch logs at full feed speed ask for over 60 PTO horsepower, which is a separate requirement from the 35 minimum. If you cannot name the tractor and the pile that justify it, you are buying capacity you will not use. I keep the extra 190 pounds and the extra horsepower out of any plan that does not need them. For a gas machine on acreage, my roundup of large property wood chippers ranks seven gas models for heavy brush piles.

Renting a 6 Inch or 8 Inch Chipper

A 6 inch wood chipper rental is the way to meet this class before you commit to a tractor-sized purchase. Ask the yard for the manual of the exact machine and a walk-through of the controls, the shutdown order and the towing setup before you leave with it. I explain what separates the two types in use in my wood chipper and brush chipper comparison.

If you search for an 8 inch wood chipper rental, apply the same rule with more weight and more power behind it. Check what your tow vehicle or tractor is rated for against the manual’s figures before you book, and keep the manual in the cab.

Safety at This Size

A chipper at this size has a powered roller, a heavy flywheel and a discharge that throws chips. The rules below are the floor. Your machine’s manual comes first wherever it is stricter, and its warnings are never softened.

Feeding and Clothing

• Hands out: Never put your hands, feet or any part of your body into the hopper, the chute or the discharge while the machine is running or the rotor is still turning, and never reach past the rubber flap or the mouth of the chute. Push short pieces in only with the paddle or push tool your manual supplies, or with the next branch or a small stick as your manual describes, never with your hand or foot.
• Feeding position: Stand to the side of the hopper or chute, never directly in front of it, and feed branches butt end first. Hold the branch near its outer end with an open hand, never wrap your fingers tightly around it, and let it go as soon as the machine draws it in; never follow a branch into the chute. Feed only the material and the branch size your manual allows, into the opening it names.
• Clothing and protection: Wear safety glasses or goggles with side shields marked ANSI Z87.1, and a full face shield where your manual asks for one; hearing protection; gloves only as your manual directs, and where it asks for gloves, snug ones without loose cuffs or drawstrings; long pants and sturdy non-slip boots; and respiratory protection as your manual requires (WEN: NIOSH-approved dust masks or other respiratory protection during operation and cleaning; Woodland Mills: a dust mask in dusty conditions). Never wear loose clothing, scarves, jewelry or dangling drawstrings, and tie up long hair: anything that catches on a branch can be pulled toward the inlet.
• Who runs it: An adult who has read the manual and understands the controls runs it, and one person feeds and handles the controls. Woodland Mills says never to allow more than one person to operate the machine at one time. A helper stays outside the work area.

Hearing protection comes first for me on any chipper I stand near, and the family is a nearer concern than a neighbour. NIOSH recommends limiting noise to 85 dBA averaged over an eight-hour workday (5), and none of the gas or PTO chipper manuals cited on this page prints a decibel figure for the machine, so I treat it as loud.

Site, Throw and Kickback

• Thrown objects and bystanders: The machine can throw chips, stones and metal out of the hopper and the discharge. Keep children, pets and other people out of the work area, at least the distance your manual prints (the Champion, MTD and Yardmax manuals ask for 75 feet), and stop the machine at once if anyone comes closer. No distance makes a work area safe on its own: keep watching it. Never point the discharge at people, animals, windows, cars or buildings, and never look into the hopper or chute while the machine runs.
• Site and weather: Set the machine on firm, level earth or grass, never on a slope, on pavement, concrete or gravel, or close to a wall or building, where chips and stones ricochet. Clear the area of stones, wire, rope and other loose objects first, and work in daylight. Never work on wet or slippery footing, where you could slip toward the inlet, never run an electric chipper in rain or in damp or wet conditions, and stop any chipper and seek shelter if you hear thunder or see lightning.
• What not to feed: Feed only clean wood and plant material that your manual allows, into the opening it names and within that opening’s limit; a leaf mulcher such as the WORX WG430, Sun Joe SDJ616 or Flowtron takes no branches, sticks or brush. Never put in stones, soil, metal, nails, wire, glass, plastic, cans or bottles, and remove soil and stones from roots first. Leave out pressure-treated wood, painted wood and lumber unless your manual allows them; several manuals ban treated and kiln-dried lumber outright.
• Kickback: If a branch will not feed, kicks back or cannot be controlled, stop feeding and let go: never chase it into the chute or try to hold it back. Remove trapped material only after the full maintenance shutdown for your power type, with every extra step your manual adds. Keep the discharge area clear: chips that build up there can make new material kick back toward you.

Starting, Stopping and Clearing

• Before every start: Check that the guards, flaps, hoppers, discharge chute and any collection bag your manual requires are fitted and secured (Earthquake forbids running without its debris bag), and that knives, fasteners, the cord or the fuel system are undamaged. If the machine starts to vibrate abnormally, stop it at once, complete the full maintenance shutdown and have the cause fixed before you restart.
• PTO models: Keep the tractor’s master shield and the driveline shields in place, connect or adjust the PTO shaft only with the tractor engine off, the key out and the driveline stopped, engage the PTO at idle, and never run a 540 RPM chipper above 540 RPM. Follow the stopping order in full before you touch the chipper.
• Gas models: Pull the starter cord slowly until you feel resistance, then pull rapidly, and never start the engine with material in the hopper or chute. Refuel a gas chipper outdoors with the engine off and cooled for at least two minutes, as the Champion and MTD manuals say, with no smoking, flames or sparks nearby; open the cap slowly, wipe spills and never start the engine where fuel spilled. Never run a gas chipper indoors or in a garage or shed, even with the doors open: the exhaust contains carbon monoxide, which you cannot see or smell. Before you start, with the engine off and cool, clear chips and dry leaves from the engine and muffler; if debris builds up during work, complete the full gas maintenance shutdown, spark plug wire off included, before you clean it away, and keep every cooling and combustible-material clearance your manual gives (Champion: 3 feet around the machine for cooling and 5 feet from combustible materials and dry vegetation; SuperHandy GUO148: 2 m, 6.5 ft, from flammable materials).
• Stopping, PTO: Throttle to idle, disengage the PTO, turn the tractor engine off, remove the key and set the parking brake, and wait until all noise and vibration have stopped. The Woodland Mills manual says the flywheel continues to spin for some time after the engine or tractor has been turned off.
• Stopping, gas: Turn the engine off and wait until the rotor and every moving part have stopped completely.
• Clearing a jam or opening the machine, gas: Never use your hand, foot or any body part to unclog the machine, even after it is shut down. Stop the engine and wait until the rotor and every moving part have stopped completely, let the engine and muffler cool, remove the key where fitted, and pull every spark plug wire off and secure it away from its plug, or ground it against the engine where your manual says so. Toro’s manual says to shut off the engine and wait five minutes to make certain the flywheel and all moving parts have come to a complete stop and cool, then remove the key and disconnect the spark plug wires. The 15 horsepower, 6 inch gas chipper manual says to shut down the engine, wait for all moving parts to come to a complete stop, remove the spark plug wire and then wait five minutes before maintenance. Five minutes is the wait those manuals prescribe, not a measured coast-down time, and the manuals do not print one.
• Clearing a jam or opening the machine, PTO: Never use your hand, foot or any body part to unclog the machine, even after it is shut down. Throttle to idle, disengage the PTO, turn the tractor engine off, remove the key, set the parking brake and wait until all noise and vibration have stopped, then disconnect the PTO shaft. Never open a hood or access panel until every moving part has stopped.
• Then clear it: Follow your manual’s own clearing steps: open only the hopper or panel it names, remove the material only with the tool it names, and refit every guard and any required bag before you restart.
• Fatigue: Feeding branches is heavy, repetitive work: take breaks, and stop when you are tired or your attention slips.

What to Remember Before You Pick a Size

The step from 6 to 8 inches costs power, weight and care. The inch number is a ceiling for one opening and one wood type, so read the manual behind it. Before you rent or buy, write down the thickest wood you feed on a normal day, check the PTO horsepower your tractor can deliver against the maker’s range, and confirm the opening and the weight with their basis. Anything past the machine’s rating is a job for a bigger rental machine with its own manual or for a professional. When the wood is smaller, my ranking of the best wood chipper for branches lists nine picks by branch capacity and budget.

My tip is to size to that normal day and read the safety section above before the first start. For most orchard and yard piles the 6 inch vs 8 inch wood chipper question never comes up, because the wood is smaller than either.

Frequently Asked Questions

What can a 6 inch wood chipper handle?

A 6 inch wood chipper handles wood up to 6 inches in diameter, according to Woodland Mills, which also lists 20 to 50 PTO horsepower and a 6 by 8 inch opening for its 6 inch model. Full-diameter logs at full feed speed take over 40 horsepower at the PTO. Anything thicker goes to a larger machine or a professional.

How much does a 12 inch wood chipper weigh?

The makers cited on this page publish no weight for a 12 inch wood chipper, so any figure would be a guess. Weight does climb with size in the machines that are documented: the Woodland Mills manuals list 710 pounds for its 6 inch PTO unit and 900 pounds for its 8 inch PTO unit. For a 12 inch machine, read the exact model’s manual and note whether its figure is net, gross or shipping weight.

Who makes the biggest wood chipper?

The makers cited on this page publish no ranking of the biggest wood chipper, so none can be named as the largest. The largest machine this page documents is the Woodland Mills 8 inch PTO model, rated for wood up to 8 inches and listed at 900 pounds in its manual. Anything bigger is not covered here, so read that exact model’s manual or hire a professional.

How to use a 6 inch wood chipper?

Use a 6 inch wood chipper only as its own manual describes: shields in place, the machine on firm level ground, the PTO engaged at idle on a tractor model, a gas towable started outdoors only, and branches fed butt end first from the side of the chute. Never reach into the infeed, and push short pieces in with another stick or branch as the Woodland Mills manual says. On the Woodland Mills PTO model, stop by throttling to idle, disengaging the PTO, turning the tractor engine off, removing the key, setting the parking brake and waiting until noise and vibration have stopped; on a gas towable, turn the engine off, wait until every moving part has stopped, let it cool, remove the key where fitted and pull every spark plug wire off, with the five-minute wait Toro’s manual prints.

What is an 8 inch PTO wood chipper?

An 8 inch PTO wood chipper is a tractor-driven chipper rated for wood up to 8 inches in diameter. According to Woodland Mills, its 8 inch model needs a tractor with 35 to 100 or more PTO horsepower and feeds through a self-contained hydraulic roller. Its manual lists a weight of 900 pounds and says only one person operates the machine at a time.

References

1. Centers for Disease Control and Prevention. Fatal and nonfatal occupational injuries involving wood chippers–United States, 1992-2002. MMWR Morb Mortal Wkly Rep. 2004;53(48):1130-1131.
2. Zhu J, Gelberg K. Occupational fatal injuries associated with mobile hand-fed wood chippers. Am J Ind Med. 2018;61(12):978-985.
3. Kearney GD, Imai S, Doub A, Langley R. Fatal incidents among tree care workers in the United States: A case series approach. J Occup Environ Hyg. 2024;21(9):629-637.
4. Hallock GG. Mutilating shredder/chipper hand injuries. Ann Plast Surg. 1994;33(1):6-8.
5. National Institute for Occupational Safety and Health. Noise-Induced Hearing Loss. Noise and Hearing Loss. Centers for Disease Control and Prevention; 2024.

Safety Note: Only an adult who has read the manual and understands the controls should use a wood chipper or shredder, never a child or anyone tired or impaired. The rotor, knives, hammers or cutting line behind the inlet can draw in a hand, a sleeve or a glove faster than you can let go, and they keep turning after you switch the machine off. Never put your hands, feet or any part of your body into the hopper, the chute or the discharge while the machine runs or the rotor still turns, never reach past the rubber flap or the mouth of the chute, and push short pieces in only with the paddle or push tool your manual supplies, or with the next branch or a small stick as your manual describes. Stand to the side of the hopper, never in front of it, feed branches butt end first with an open hand near the outer end, and let go as soon as the machine draws the branch in; if a branch kicks back or will not feed, stop feeding and let go, never chase it into the chute. Feed only the clean material your manual allows, into the opening it names and within that opening’s limit (a chipper chute and a shredder hopper have different limits, and a leaf mulcher takes no branches, sticks or brush), and never stones, soil, metal, nails, wire, glass or plastic. The machine can throw chips, stones and metal: keep children, pets and other people out of the work area, at least the distance your manual prints (the Champion, MTD and Yardmax manuals ask for 75 feet), stop at once if anyone comes closer, and never point the discharge at people, animals, windows, cars or buildings. Set the machine on firm, level earth or grass, never on a slope, on pavement, concrete or gravel, or close to a wall, work in daylight, never work on wet or slippery footing where you could slip toward the inlet, never run an electric chipper in rain or in damp or wet conditions, and stop and seek shelter for thunder or lightning. Wear safety glasses or goggles with side shields marked ANSI Z87.1, a face shield where your manual asks for one, hearing protection, gloves only as your manual directs (snug ones without loose cuffs or drawstrings where it asks for them), long pants and sturdy non-slip boots, and respiratory protection as your manual requires (WEN asks for NIOSH-approved dust masks or other respiratory protection during operation and cleaning); never wear loose clothing, scarves, jewelry or dangling drawstrings, and tie up long hair. Before every start, check that the guards, flaps, hoppers, discharge chute and any collection bag your manual requires are fitted and secured, and stop at once if the machine starts to vibrate abnormally, complete the full shutdown below and have the cause fixed before you restart. Never use your hand, foot or any body part to unclog the machine, even after it is shut down. Before you clear a clog, open the hopper or a panel, touch the knives, empty the bag, move or tilt the machine or leave it: on an electric hopper chipper, switch it off, unplug it from the outlet by the plug and wait until the blades have stopped completely, and on a leaf mulcher switch it off, wait until all motion has stopped and unplug it by the plug, never opening any electric machine before it is unplugged and still; on a gas chipper, follow your manual’s own shutdown sequence and every wait it prints: the engine off, the rotor and every moving part stopped completely, the engine and muffler cooled, the key removed where fitted, and every spark plug wire pulled off and secured away from its plug or grounded where your manual says so; on a PTO chipper, throttle to idle, disengage the PTO, turn the tractor off, remove the key, set the parking brake, wait until all motion has stopped and disconnect the PTO shaft before any service. Complete every model-specific step and minimum wait in the order your manual prescribes before any access, clear the blockage only with the method and tool it names, and refit every guard and any required bag before you restart. Use an electric chipper only with an outdoor-rated extension cord of the gauge and length your manual gives, plugged into GFCI-protected power, and never touch it or the plug with wet hands. Refuel a gas chipper outdoors with the engine off and cooled for at least the time your manual gives (Champion and MTD: two minutes), open the cap slowly, keep smoking, flames and sparks away, wipe up spills and never start it where fuel spilled; clear chips and leaves from the engine and muffler only after the full shutdown, spark plug wire off included, keep every cooling and combustible-material clearance your manual gives (Champion: 3 feet around the machine for cooling, 5 feet from combustible materials and dry vegetation), and never run it indoors or in a garage or shed, even with the doors open, because the exhaust contains carbon monoxide. Take breaks and stop when you are tired.