Chainsaw gauge is the thickness of the drive links on the underside of the chain, and it has to match the width of the groove in the guide bar. Gauge is one of three numbers, with pitch and drive link count, that decide whether a chain fits your saw. I order parts for farm machines the same way: a part that is nearly right is the wrong part. Below you get the four common gauge sizes, where to read yours, and what goes wrong when the numbers disagree.
What Does Chainsaw Gauge Mean? The Short Answer
Gauge is a thickness. According to Husqvarna, it is the thickness of the lower part of the chain drive link and the width of the guide bar groove. Oregon, a saw chain maker, puts it the same way: the gauge of the chain and the gauge of the bar must match.
The drive links are the small tabs that hang down from the chain. They ride in a groove that runs around the edge of the bar, and they keep the chain on the bar while the sprocket pulls it. A chain whose links are too thick or too thin for the groove is the wrong chain, even when it has the right length. My guide to what a chainsaw is names the main parts and types.
Gauge is measured in inches or millimeters. Four sizes are common, and the table below lists them. People also type the phrase chainsaw gauge when they mean a different part, the depth gauge, which I cover in its own section further down.
Three Numbers Decide the Fit
A replacement chain must match the pitch, the gauge and the number of drive links your saw and bar call for. The manual of your exact saw lists them, and the numbers are often etched on the bar.
Where the Drive Links Sit
Gauge makes sense once you see the three parts that meet at the chain: the bar, the drive links and the sprocket. Each part has a size, and the gauge is the size that connects the first two.
The Bar Groove
The guide bar has a channel cut along its edge. Oregon describes chain gauge as the drive link thickness where it fits into this groove. The groove width and the chain gauge are the two halves of one fit, which is why a chainsaw bar gauge number is printed on the bar itself.
The Sprocket and the Cutters
The sprocket engages the drive links and pulls the chain around the bar. The cutters, the teeth that do the cutting, are joined to the drive links by rivets, according to Alabama Extension. Because the links carry the whole drive, a link that fits loosely or tightly in the groove is more than a cosmetic problem. My guide on how does a chainsaw work shows how the engine, clutch, chain and brake fit together.
When I take a dead plum limb apart with a saw, I think about the chain as a belt that happens to have teeth. A belt that does not sit properly in its pulley groove is a problem on any machine, and the same logic applies here.
Chainsaw Chain Gauge Sizes
Four gauge sizes are common, according to UGA Extension. The chainsaw gauge chart below lists the four common sizes, and the manual of your exact saw says which one it takes.
| Gauge in inches | Gauge in millimeters | Where it appears |
|---|---|---|
| .043 | 1.1 | Listed by UGA Extension and Oregon |
| .050 | 1.3 | Listed by UGA Extension and Oregon; the .325-inch-pitch chain listed for the Husqvarna 435 and 440 |
| .058 | 1.5 | Listed by UGA Extension and Oregon |
| .063 | 1.6 | Listed by UGA Extension and Oregon |
UGA Extension prints the first size as .43, and the real size is .043 inch, which Oregon also writes. A .043 gauge chainsaw chain has the thinnest links of the four, and it is also called a 1.1 mm chain. Which gauge a saw takes is a question for the manual of that saw: the Husqvarna 435 and 440 manual lists .050 inch, and the EGO CS1800E manual in the EU edition gives 1.3 mm.
Do not guess a gauge from the size of the saw. Gauge does not follow engine size or bar length by any fixed rule, so the only safe answer is the number in the manual or on the bar. My guide to cc on a chainsaw explains engine size in plain terms.
Chainsaw Gauge and Pitch Are Two of Three Matching Numbers
Gauge is only one of three numbers on a chain. A chain fits when its pitch, its gauge and its drive link count all agree with the saw and the bar, and a chain that gets two of the three right still does not fit.
Pitch is the overall size of the chain, according to UGA Extension, and it has to match the drive sprocket and the bar tip. Common pitch sizes are .25 inch, .325 inch, .375 inch (3/8 inch) and .404 inch. Pitch has its own article on this site, my guide to what chainsaw pitch means, so I keep it short here. Chainsaw pitch and gauge describe different dimensions: pitch is the chain’s overall size, and gauge is the thickness of the drive links.
The drive link count is printed on the chain and in the manual’s bar and chain table. It changes with bar length: the Echo CS-590 manual lists 60 links for a 16 inch bar, 66 for 18 inch, 70 for 20 inch and 84 for 24 inch, according to Echo. The Husqvarna 435 manual lists 56 links for a 13 inch bar and 64 for 15 inch. My guide on what size chainsaw do I need covers bar length for homeowners.
- Pitch: the chain’s overall size; it must match the sprocket and the bar tip.
- Gauge: the drive link thickness; it must match the bar groove.
- Drive link count: how many links fit around your bar; it follows the bar length.
How to Find Your Chainsaw’s Gauge
You can find the gauge without measuring anything in most cases. Three places carry it, and I check them in this order.
Read the Bar First
Chain makers laser etch the chain pitch and gauge at the rear of the bar, according to UGA Extension, so that you can order a chain to match. Husqvarna says the gauge is often printed on the tail of the bar. The paint wears off with use, which is why I read the bar before the saw is dirty.
Use the Old Chain or the Manual
Oregon tells buyers to order by the number stamped on the drive link of the old chain. The operator’s manual of your exact saw lists the approved bar and chain combinations, and it is the final word. If the numbers cannot be read, Husqvarna and Stihl both advise asking a dealer for help.
- Stop the saw with the Maintenance order in the box below, so that the chain cannot move.
- Look at the rear of the bar for the etched pitch and gauge.
- Check the drive link for a stamped number if you are holding the chain.
- Compare both with the bar and chain table in your manual.
- Take the bar or the old chain to a dealer if any number is unreadable.
Stop and Make the Saw Safe First
Release the trigger, engage the chain brake if the saw has a lever, switch the engine or motor off and wait until the chain has stopped. Then on a gas saw let the engine and muffler cool and pull the spark plug cap off; on a battery saw take the battery out; on a corded saw pull the plug from the outlet by the plug, not the cord. Put on gloves before touching the chain. Release the chain brake only when your manual’s procedure requires it, and never force a locked chain or cover.
In the orchard I do this kind of check at the shed bench, on a cold saw, with the gloves already on. The bar shows me the numbers, and I write them on the side of the toolbox.
What Happens When the Gauge Does Not Match
The rule is short and the makers state it plainly. Oregon states that the gauge of the chain and the gauge of the bar must match. Stihl says a mismatch can make the chain wobble and come off the bar.
A chain that comes off the bar at speed is a hazard to the operator, which is the reason the rule is strict. Wrong parts also feed the kickback risk. The Echo CS-590 manual warns that a replacement chain or bar other than the one specified may cause severe kickback, and Husqvarna warns that other bar and chain combinations may not meet the kickback requirements listed for the saw.
If the upper part of the bar tip touches wood or another object, the bar can kick back up and toward you (rotational kickback). Wood pinching the chain on the top of the bar pushes the saw straight back at you (pushback), and wood pinching the bottom pulls it forward, away from you (pull-in). A low-kickback chain, a chain brake and a correct grip reduce these risks; none removes them, and no safety feature makes a chain that does not fit the bar acceptable. I keep a low-kickback chain on any saw for home use and I buy only the chain the manual lists.
Do Not Confuse Chain Gauge With Depth Gauge
The word gauge appears twice on a chain, and it means two different things. The chain gauge is the drive link thickness. The chainsaw depth gauge is a small step in front of each cutter that limits how deep the cutter bites.
The depth gauge matters when you sharpen. Alabama Extension warns that filing too much of the depth gauge makes the tooth remove too much wood and bind up, and Husqvarna says a depth gauge setting that is too large increases the risk of kickback. If you are not sure how to sharpen, Clemson recommends having the chain professionally sharpened. This article does not teach sharpening, because the right figures sit in your manual.
Two other tools carry the same word and have nothing to do with the chain: a tachometer and a compression gauge. I leave them out here.
Reading a Chain Box Before You Buy
A worked example shows how the three numbers work together. The Husqvarna 435 manual lists a pitch of .325 inch, a gauge of .050 inch and 64 drive links for a 15 inch bar.
| Number | The saw calls for | Matching dimensions | A chain that does not |
|---|---|---|---|
| Pitch | .325 inch | .325 inch | 3/8 inch |
| Gauge | .050 inch (1.3 mm) | .050 inch | .058 inch |
| Drive links | 64 for 15 inch | 64 | 56 |
A chain marked .325 pitch and 64 links is still the wrong chain if it is a .058 gauge chainsaw chain, because the links are thicker than the groove. The pitch and the count agree, and the fit fails on the third number. This table shows dimensions only: it does not replace the approved bar and chain combinations in your manual.
On my farm I have learned to read a spare part’s numbers at the counter instead of at the machine. A trip back to the shop is a cost in time, and the numbers cost nothing to check before I leave. I use the same habit for a saw chain.
Why the Right Chain Matters for Safety
None of the research below measures chain gauge itself. It does show why a correctly fitted chain deserves a few minutes of care, and each study is described for what it found.
What the Kickback Research Found
Laboratory tests on a standard kickback test stand looked at gas saws. The author names proper chain tension, anti-kickback chain links, guide bars with sliding ends and a quickly activated chain brake as influences on kickback (1). The study did not look at gauge. It does show that the chain and bar parts, and how they are set, shape what happens in a kickback.
A second laboratory study found that kickback risk depends on the wood being cut and on where the bar tip touches it (2). Together the two studies tell me that the saw, the chain and the cut all matter, and the chain is the part I can control with a manual and a few numbers.
Who Gets Hurt
In US emergency department data for 2006 to 2016, power saws caused 89 percent of 18,250 saw and axe injuries, mostly cuts to the fingers and hand, and most happened at home (3). The power saw group in that study includes more than chainsaws.
A review of 185 patients treated for non-occupational chainsaw injuries in rural areas found leg injuries in 109 and arm injuries in 76 patients, and the authors concluded that protective gear and simple precautions can prevent such injuries (4). An Irish survey of 62 domestic accidents found that only 3 percent of the injured users wore any protective gear, and its authors found a general lack of appreciation of the risks (5).
None of these studies is about chain gauge, and I do not claim they are. They show that home users get hurt in ordinary jobs, and that care before the cut is worth the time. Matching the chain to the bar is part of that care. So is protective gear: wear impact-rated safety glasses with side protection marked Z87+ (a mesh face screen adds to them but never replaces them), hearing protection, chainsaw chaps or chainsaw trousers used within their maker’s stated limits (some are not designed to stop a battery or corded saw’s chain, and no clothing guarantees protection), work gloves and sturdy boots with ankle support, plus a hard hat when you fell a tree or anything can fall from above.
Three Numbers to Write Down
Remember three things. Gauge is the drive link thickness and it must match the bar groove. Pitch, gauge and drive link count must all agree with the saw. The manual of your exact saw has the final answer, and a dealer can read what you cannot.
My tip from the orchard is simple: when a chain is on the saw and in good order, write the three numbers on a piece of tape on the bar cover. Then a trip to buy a new chain starts with the answer to the question of chainsaw gauge already in your pocket.
Frequently Asked Questions
What is the gauge on a chainsaw chain?
The gauge on a chainsaw chain is the thickness of its drive links, the tabs that ride in the bar groove. Common sizes are .043, .050, .058 and .063 inch, according to UGA Extension, and the number must match the bar.
What are the drive links on a chainsaw?
The drive links on a chainsaw are the tabs on the underside of the chain that sit in the bar groove and are pulled around by the sprocket. The cutters are joined to them by rivets, according to Alabama Extension.
Does chainsaw chain gauge matter?
Chainsaw chain gauge matters because the drive links must fit the bar groove, and Oregon states that the gauge of the chain and the gauge of the bar must match. Stihl says a mismatch can make the chain wobble and come off the bar.
Can I use a .043 chain on a .050 bar?
A .043 chain should not go on a .050 bar, because the chain gauge and the bar gauge must match, according to Oregon. The thinner links would sit loosely in the wider groove, and Stihl says a mismatch can make the chain wobble and come off. Use the chain your manual lists for that bar.
Are all 18 inch chainsaw chains the same?
Chains for an 18 inch bar are not all the same, because pitch, gauge and drive link count can each differ. The Echo CS-590 manual lists 66 drive links for its 18 inch bar, and a saw with another pitch or gauge needs another chain.
References
- Dąbrowski A. Reducing kickback of portable combustion chain saws and related injury risks: laboratory tests and deductions. Int J Occup Saf Ergon. 2012;18(3):399-417.
- Dąbrowski A. Kickback risk of portable chainsaws while cutting wood of different properties: laboratory tests and deductions. Int J Occup Saf Ergon. 2015;21(4):512-523.
- Sritharen Y, Hernandez MC, Zielinski MD, Aho JM. Weekend woodsmen: overview and comparison of injury patterns associated with power saw and axe utilization in the United States. Am J Emerg Med. 2018;36(5):846-850.
- Özdeş HU, Ergen E, Köroğlu M, et al. Chainsaw-related extremity injuries. Medicina (Kaunas). 2025;61(4):759.
- Doyle YG, Conroy RM. Prevention of timber felling and chainsaw-related accidents in the Republic of Ireland. Accid Anal Prev. 1989;21(6):529-534.
Safety Note: Read your saw’s manual first and get hands-on training before your first cut. A chainsaw can react faster than you can: if the upper part of the bar tip touches wood or another object, the bar can kick back up and toward you; wood pinching the top of the chain can push the saw straight back at you, and wood pinching the bottom can pull it forward. Keep the bar tip out of contact and watch for wood closing on the bar. A low-kickback chain and a chain brake reduce these risks but never remove them. Before each use, inspect the saw as your manual describes: test the chain brake, and check the throttle lockout, the stop switch, the chain catcher, the guards and the chain. On a gas saw the chain must not move at idle. If any check fails or a part is missing or damaged, do not use the saw until it is repaired, and never disable a safety device. Wear impact-rated safety glasses with side protection marked Z87+ (a mesh face screen adds to them but does not replace them), hearing protection, chainsaw chaps or chainsaw trousers, work gloves and sturdy boots with ankle support, and a hard hat when you fell a tree or when anything can fall from above. Use leg protection within its maker’s stated limits: some chaps are not designed to stop the chain of a battery or corded saw, and no clothing guarantees protection. Hold the saw with both hands, right hand on the rear handle and left hand on the front handle, thumbs and fingers wrapped around the handles, and keep your body to the left of the chain line with firm footing. Never cut one-handed with a rear-handle saw, never cut at or above shoulder height, and never cut from a ladder or a roof. Top-handle saws are made for trained tree workers: follow that saw’s manual. Keep children, bystanders and pets well away while you cut. Never work alone. Start a gas saw with the chain brake engaged, on the ground or held firmly as the manual shows, never by drop-starting it, and at least 10 feet from where you fuelled it. Refuel outdoors with the engine off and cool, with no smoking, flames or sparks nearby, wipe up spills, and use only the fuel mix and ethanol content your manual allows. Exhaust contains carbon monoxide, which can kill: never run a gas saw indoors or in a garage, shed or other enclosed space. Before you touch the chain, clear a jam, adjust the tension or sharpen: release the trigger, engage the chain brake, stop the engine or motor and wait until the chain has stopped. Then, on a gas saw, let the engine and muffler cool and pull the spark plug cap off; on a battery saw, take the battery out; on a corded saw, unplug it by the plug. Put on gloves before you touch the chain, and release the chain brake only when your manual’s procedure calls for it. To carry the saw, stop it, take out the battery or unplug it, keep the chain brake engaged and the bar pointing behind you, and fit the bar cover for transport. Use a corded saw only with an outdoor-rated extension cord of the gauge your manual gives, plugged into GFCI-protected power. Never use it in rain or wet conditions: GFCI protection does not make that safe. Keep the cord away from the chain. Use only the chains and bars your manual approves. Felling trees is the most dangerous chainsaw job. Before any felling cut, keep everyone at least two tree lengths away, and plan and clear two escape routes angled back from the direction of fall; when the tree starts to fall, follow your manual’s retreat steps (release the trigger, stop the saw and set it down as it describes) and move away along that route; never delay escape to cool, unplug or cover the saw. A large, leaning, dead or hung-up tree, a trunk or limb under tension after a storm, and any tree near a house or a road are jobs for a certified arborist. Power lines are a separate danger: treat every downed line, and anything touching it, as live, stay well away and call the utility; before any work near a power line, contact the utility and leave that work to its qualified line-clearance crews. Stop when you are tired, and take breaks if your hands tingle or go numb.