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CFM vs MPH vs newtons: which leaf blower number to trust
Updated
Buy by CFM first. CFM (cubic feet per minute) is how much air leaves the tube, and volume is what moves a pile. MPH is how fast that air goes, and makers measure it with the narrow nozzle on. Newtons of blowing force fold both into one number, but few makers print it.
Why MPH flatters small blowers
Squeeze the same air through a smaller hole and it speeds up. EGO's page for the LB7654 says so directly: 765 CFM and up to 200 MPH "with the tapered nozzle attached". A narrow nozzle raises MPH without adding any air.
The clearest case on this site is the BLACK+DECKER LSW221. Its listing shows 130 MPH, the same as the Greenworks 40V 550. But it moves 100 CFM and the Greenworks moves 550. Same speed on paper, about one fifth of the air. One sweeps a porch. The other clears a lawn.
- EGO LB7654765 CFM
- Greenworks 80V700 CFM
- EGO LB6151615 CFM
- Greenworks 40V550 CFM
- Makita XBU03Z459 CFM
- WORX WG547360 CFM
- BLACK and DECKER LSW221100 CFM
What each number is good for
| Number | What it tells you | Watch out for |
|---|---|---|
| CFM | How much air moves. More CFM pushes a wider, deeper pile | It is the turbo figure. The dial range is lower |
| MPH | How hard the air hits. Helps lift wet, matted leaves and clear cracks | Measured with the narrow nozzle. High MPH with low CFM is a sweeper, not a yard tool |
| Newtons (N) | Blowing force. One number that reflects both speed and volume | Most listings do not show it |
Where newtons come from
Some makers publish a blowing force. Husqvarna, for example, lists its 350iB handheld at 23.5 N max blow force. Makers often point to ANSI/OPEI B175.2 as the method. It is worth knowing what that standard covers. ANSI's own summary says it applies to internal combustion engine-powered handheld and backpack blowers, and that it does not apply to electrically powered units. So when a battery blower quotes a newton figure, the maker is borrowing the method by choice. That is still useful, but you cannot assume two brands measured the same way.
None of the seven Amazon listings we read gives a newton figure. If a listing you are looking at does, compare it only with other newton figures, and prefer it over MPH.
A quick way to read a listing
- Find CFM. Under 400 is a hard-surface sweeper. 400 to 600 handles most lawns. 600 and up is for big yards, heavy leaf fall and wet leaves.
- Check that MPH is at least in the same league as others in that CFM class. Ignore small differences.
- Then go straight to the battery. See turbo mode and runtime.
Plan your own yard with the battery calculator, or compare all seven picks on the roundup page.