Blow force on a leaf blower is the push of the air jet where it leaves the nozzle, rated in newtons. It comes from two things at once, the volume of air the fan moves and the speed of that air, so the blower with the highest mph on the box is often not the one that pushes hardest.
I read the newton figure before CFM or MPH on a spec sheet, because it already holds the other two. Below you will find how volume and speed make force, what real maker ratings show, how the figure is tested, and what it leaves out.
What Is Blow Force on a Leaf Blower?
Blow force is the thrust of the air stream at the nozzle. It is the same kind of push a jet engine makes, only far smaller. Husqvarna describes blowing force as the overall pushing power of the blower, and Echo prints it as “Newtons (N) at nozzle” beside the air volume and air speed.
A newton is the SI unit of force, equal to one kilogram meter per second squared (1). One pound-force equals about 4.45 newtons (2), so 1 N is about 0.225 lb of push. A 22 N blower pushes with about 5 lb, and a 48 N gas backpack with about 11 lb.
Makers use the figure to compare blowers. According to Stihl, the newton row is there “to compare the performance of blowers,” and according to Husqvarna, blowing force is generally the more reliable indicator when you compare performance.
How Air Volume and Speed Make Blow Force
Air has mass, about 0.075 lb per cubic foot, and a fan throws a certain amount of it out of the tube every second. Each pound leaves at a speed. The push equals the mass of air leaving each second times its speed, the same rule NASA Glenn gives for thrust: it depends on how much gas is accelerated and on how much its speed changes (3).
In blower terms, CFM says how much air leaves each minute and MPH says how fast it goes. For an ideal jet, where all the air leaves at one speed, multiplying the two and scaling for the weight of air gives the push, so a change in either number changes the force by the same share. A real sheet lists peak figures that do not all occur at once, so this sum runs above what makers rate. Read the sums below as a picture of how the numbers move, not as a way to find a blower’s real force.
Doubling Volume or Speed Doubles the Push
Take an ideal jet of 500 CFM at 100 mph. The sum comes to about 12.7 N, or 2.9 lb of push. Double the air and the push doubles, and so does doubling the speed. The table shows the pattern with round figures picked for teaching, not a rated blower.
| Case | Air volume | Air speed | Push |
|---|---|---|---|
| Starting point | 500 CFM | 100 mph | About 12.7 N (2.9 lb) |
| Double the air | 1,000 CFM | 100 mph | About 25.3 N (5.7 lb) |
| Double the speed | 500 CFM | 200 mph | About 25.3 N (5.7 lb) |
| Half the air at twice the speed | 250 CFM | 200 mph | About 12.7 N (2.9 lb) |
The last row gives the same sum as the first, because halving the air and doubling the speed cancel out. A tapered nozzle makes that trade: it raises speed and cuts volume. On paper it adds no push, and in a real blower the total stays about the same or drops, while the push on a small spot rises. That helps on a seam between slabs and does not make the blower stronger.
Why a Thin, Fast Jet Pushes Little
Speed cannot rescue a small fan. A jet of 100 CFM at 130 mph works out to about 3.3 N, or 0.7 lb of push, a small fraction of the 17 N to 48 N that the maker-rated blowers in the table below list. I read a big mph claim on a small blower with suspicion until I see the CFM beside it.
My guide on how the CFM rating is defined and where it is measured covers that volume figure and how two blowers with the same CFM can still feel very different.
Speed is also the costly way to make push. For the same 25 N, an air stream at about 112 mph carries roughly 0.8 horsepower of energy per second, and one at about 224 mph carries roughly 1.7 horsepower, before any loss in the motor and fan. A large fan moving a lot of air gently makes the same push for less fuel or battery, which is one reason gas backpacks have big fans.
Why Blow Force Predicts Clearing Power Better Than CFM or MPH Alone
A rating of CFM alone ignores how fast the air moves, and a rating of MPH alone ignores how much air there is. Leaf blower newtons put both on one scale. According to Husqvarna, blowers with a higher rating are better suited to clearing wet leaves.
Same Speed, Double the Air
Echo’s three gas backpack models show the product at work. According to Echo, the PB-580T moves 517 CFM at 216 mph for 22 N, and the PB-9010T moves 1,110 CFM at 220 mph for 48 N. The speed barely changed, the air volume went up 2.1 times, and the force went up 2.2 times.
| Blower | CFM | mph | Force | In pounds |
|---|---|---|---|---|
| Echo PB-580T (gas backpack) | 517 | 216 | 22 N | 4.9 lb |
| Echo PB-770T (gas backpack) | 756 | 234 | 33 N | 7.4 lb |
| Echo PB-9010T (gas backpack) | 1,110 | 220 | 48 N | 10.8 lb |
| Husqvarna 150BT (gas backpack, round nozzle) | 452 | 270 | 22 N | 4.9 lb |
| Husqvarna 580BTS (gas backpack) | 1,000 | 220 | 47 N | 10.6 lb |
| Milwaukee M18 FUEL dual battery blower 2824-20 (cordless) | 600 | 145 | 17.7 N | 4.0 lb |
The fastest air in the table is not the strongest push. According to Husqvarna, the 150BT is rated 270 mph at the round nozzle and 22 N, while the 580BTS is rated 220 mph and 47 N. The slower blower pushes more than twice as hard, because it moves more than twice the air. When I put the 150BT’s 22 N beside the 580BTS’s 47 N, the 270 mph stopped impressing me.
A Rough Check From the Box Numbers
A maker that prints CFM and mph but no newtons leaves you only those two numbers. As a rough check, multiply CFM by mph and divide by 5,000. The divisor is a fit to makers’ published figures, which sit below the ideal sum, and it is not a test or a standard.
For the Echo PB-9010T it gives 48.8 N against the rated 48 N, and for the Milwaukee it gives 17.4 N against the 17.7 N it lists. On every model in the table it lands within about a fifth of the rating. It cannot give you a blower’s real force, and it is no way to rank blowers: it only shows whether the three numbers on a sheet fit together.
The check works only when both numbers describe the same point and mode. Husqvarna lists the 150BT at 452 CFM at the round nozzle and 765 CFM in the housing. With 270 mph, the nozzle figure gives 24 N and the housing figure 41 N, against a rating of 22 N. A CFM read at the housing flatters the blower, so the printed newton figure is the number to trust.
How Makers Test and Rate Blow Force
A blow force rating is a measurement taken at the nozzle, and makers say so on the sheet. Echo labels its rows “Air Volume at Nozzle,” “Maximum Air Speed at Nozzle” and “Newtons (N) at Nozzle.” Husqvarna lists air flow separately for the round nozzle, the housing and the pipe, so you can see which point each CFM figure belongs to.
What the Standard Covers
Makers of gas blowers cite the ANSI/OPEI B175.2 standard. It covers handheld and backpack blowers with combustion engines and includes a procedure for measuring blowing performance. It excludes electric units, and the procedure itself sits in the paid standard.
A battery maker may set up its own test, so any leaf blower newton force figure is only as comparable as the test behind it. Compare numbers within a brand or a class. Check also whether the speed is a peak or an average: Stihl lists the BR 800 C-E at 199 mph average and 239 mph maximum, and the choice moves the arithmetic by a fifth.
Who Prints a Newton Rating
Echo, Stihl and Husqvarna print newtons on their spec sheets. Milwaukee lists 17.7 N for the M18 FUEL dual battery blower. Many cordless makers print only CFM and mph. For those blowers, compare within a class and read both numbers for the same mode.
What Blow Force Does Not Tell You
A newton rating is one number taken at one place, so it leaves out several things that matter in the yard. I checked seed drills on weighing trays for the same reason: the label gives the setting, and the tray shows what lands.
- Distance: The rating is taken at the nozzle. A jet pulls in the still air around it, and the amount depends on the jet’s momentum and its distance from the nozzle (4). Models of a round jet built on momentum matched air-jet experiments (5), so the stream widens and slows as it travels. On the gravel yard I keep the tip two to three feet from the stones and check that no person and no window is in the line of throw.
- Spread: Force is the total push, not the push on each square inch. A tapered nozzle packs the push into a smaller spot, and a wide nozzle spreads it over more.
- Runtime: The rating is the push at full trigger or Turbo, and it says nothing about minutes. According to EGO, the LB7654 gives up to 15 minutes on Turbo and up to 150 minutes on low. I plan the quarter-acre lawn by my house in the minutes the pack gives on high, not the minutes the box lists on low.
- Surface and moisture: Wet leaves on grass and dry leaves on concrete ask for different technique. On the yard concrete a wet leaf mat only slid under a fast, thin stream, and it rolled once I had more air behind it. No maker gives a newton value per job, so the figure ranks blowers and does not size a job.
- Noise and weight: The figure says nothing about the load on your back or your ears. Fuel-powered blowers gave landscaping workers significantly more noise and carbon monoxide exposure than battery versions in a NIOSH sampling study (6). With a gas backpack on my hips I put plugs and earmuffs on before the engine starts.
Hearing and Eye Protection
Wear earplugs and earmuffs together from the first minute on a gas backpack, and eye protection on every blower. Add a dust mask for dusty work, stop and cool a gas engine before you refuel, and keep people and windows out of the debris path.
How to Use Blow Force When You Compare Blowers
Use blow force as the first filter, then let runtime, weight and noise decide. These six steps keep the comparison honest.
- Find the newton figure first. Look for “Newtons” or “blowing force” on the maker’s spec sheet, usually beside air volume and air speed.
- Check what the numbers describe. Make sure the CFM and the mph on a sheet describe the same point and the same mode before you set one blower beside another. If a sheet prints no newton figure, compare only blowers of the same class.
- Note the mode, the nozzle and the test. Write down which mode and which nozzle each figure belongs to, and compare two blowers only when their sheets show the same operating conditions. A word such as Turbo on two sheets does not prove the two makers measured alike.
- Compare within a class. A 17 N cordless handheld and a 48 N gas backpack are different machines for different yards.
- Check the runtime on high. The rating is a peak, so ask how many minutes the pack or the tank gives at that push.
- Add weight and noise. A 48 N backpack on your hips for an hour is a different job from a 17 N handheld, and it needs hearing protection from the start.
The mistake I see most is comparing a gas rating with a cordless rating as if the test were the same. The next is buying on newtons without checking the minutes on high.
Expert Tip
I put each candidate on one row with CFM, mph, newtons and the point each number was taken at. A row with a gap in it is the blower I look at twice.
Read Blow Force Before CFM and MPH
Three points carry this guide. Blow force is the push of the air jet at the nozzle, in newtons. It comes from air volume and air speed working together. And the rating does not say how hard that jet pushes a patch of leaves farther out, because the stream widens and slows as it travels.
Along the orchard alley I hold the tip low and close, under the leading edge of the leaf mat, for that reason. The leaf blower guides list models by class. Check the spec sheet for a newton figure before anything else, because blow force on a leaf blower is the one rating that already counts volume and speed together.
Frequently Asked Questions
How do I make my leaf blower more powerful?
You cannot add much power to a leaf blower, because the push comes from the size of the fan and the strength of the motor or engine. A freshly charged battery or fresh fuel mix, a clean air filter or intake screen, and the nozzle your maker’s speed figure assumes let the blower reach the force it was built for. A narrow nozzle raises speed but cuts volume, so it changes where the push lands more than how much of it there is.
What is blow force on a Stihl leaf blower?
Blow force on a Stihl leaf blower is the push of the air jet at the nozzle, listed in newtons so that you can compare models. According to Stihl, the figure is given “to compare the performance of blowers,” and the BR 800 C-E gas backpack is rated 41 N. The cordless BGA 100 is rated 17 N and the BGA 200 21 N.
What is blow force on an electric leaf blower?
Blow force on an electric leaf blower is the same quantity as on a gas model: the push of the air jet at the nozzle, in newtons. Many cordless makers print only CFM and mph, so look for a newton figure on the spec sheet, such as the 17.7 N Milwaukee lists for its M18 FUEL dual battery blower or the 23.5 N Husqvarna lists for the 350iB. When none is printed, compare blowers in the same class and read the CFM and mph for the same mode.
How do you calculate newton force on a leaf blower?
To calculate newton force on a leaf blower, multiply the mass of air leaving the nozzle each second by its speed. That means turning CFM into cubic meters per second, turning that into kilograms with the density of air, about 1.2 kilograms per cubic meter, and multiplying by the speed in meters per second. The result runs above what makers rate, because the speed on the box is often a peak in the middle of the jet, so the maker’s printed rating is the number to trust.
Is CFM or MPH better?
Neither CFM nor MPH is better on its own, because blow force comes from both multiplied together. A blower with half the speed and twice the volume can push just as hard.
References
- Newell DB, Tiesinga E, eds. The International System of Units (SI). NIST Special Publication 330, 2019 Edition. National Institute of Standards and Technology; 2019.
- Thompson A, Taylor BN. Guide for the Use of the International System of Units (SI). NIST Special Publication 811, 2008 Edition. National Institute of Standards and Technology; 2008.
- NASA Glenn Research Center. Thrust Equation. Beginners Guide to Aeronautics. Updated June 10, 2026.
- Ricou FP, Spalding DB. Measurements of entrainment by axisymmetrical turbulent jets. J. Fluid Mech. 1961;11(1):21-32.
- Franco Medrano F, Fukumoto Y, Velte CM, Hodžić A. Mass Entrainment Rate of an Ideal Momentum Turbulent Round Jet. J. Phys. Soc. Jpn. 2017;86(3):034401.
- Alexander BM, Graydon PS, Pena M, Feng HA, Beamer BR. Hazardous exposures and engineering controls in the landscaping services industry. Journal of Occupational and Environmental Hygiene. 2025;22(3):189-202.
Safety Note: Leaf blowers throw debris and can damage your hearing. Wear eye and ear protection, read the manufacturer’s manual, and check your local rules on noise and operating hours.