CFM vs MPH: The Leaf Blower Number Almost Everyone Reads Wrong
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There are two numbers on the side of every leaf blower box. Most people read the wrong one.
MPH is printed bigger, sounds more impressive, and is the one shoppers compare. CFM sits underneath in smaller type and is the one that actually decides whether you clear the lawn in fifteen minutes or spend an hour pushing the same damp pile around.
Here is the difference, in plain terms, so you can read a spec sheet properly before autumn arrives.
MPH is the speed of the air. CFM is how much of it there is.
MPH — miles per hour — measures how fast air leaves the tube. Think of it as the sharpness of the jet.
CFM — cubic feet per minute — measures the volume of air being moved. Think of it as how much air arrives.
A useful way to picture it: a thumb over the end of a garden hose gives you high speed and very little volume. It will cut a line through gravel but it will not shift a puddle. Take your thumb off and the speed drops while the volume rises — and suddenly you can move water across a whole driveway. Leaves behave the same way.
The short version
High MPH with low CFM blasts a narrow line and scatters everything either side of it. High CFM moves a wide mass of leaves in one direction and keeps them together. For clearing a lawn, CFM is the number that matters.
The test that separates real blowers from loud ones
Anything will move a dry leaf on a still day. The honest test is three days after rain, when the leaves have gone flat and dark and glued themselves to the grass.
A high-MPH, low-CFM blower will drill a hole through that mat and leave the rest stuck down. You end up walking the same strip four times. Volume is what gets underneath a wet layer and peels it up — which is why a blower rated around 600 CFM or more finishes a job that a 350 CFM machine turns into an afternoon.
So what number do you actually need?
For a normal suburban lot — a lawn, a driveway, a patio and a garage floor — the useful range starts around 500 CFM and gets comfortable above 600. Below about 400 CFM you are buying a duster: fine for a balcony or a workbench, frustrating on a lawn in November.
MPH still matters, just less. You want enough speed to break leaves loose from grass — somewhere around 150 to 200 MPH does that. Past that, extra MPH mostly buys you noise and a narrower working width.
How our two blowers read on this scale
40V Cordless — 680 CFM at 210 MPH
Comfortably above where the job gets done on a normal lot, with enough speed to lift wet leaves. Brushless motor, variable speed for gravel and flower beds, and a turbo button for the matted stuff. Two 5.2Ah batteries and two chargers, so both packs fill at once and the lawn gets finished in one go.
Two tubes in the box: a long one for open lawn, a tapered one that concentrates the same air for corners and fence lines.
4-Stroke Backpack — 75.6cc
A different tool for a different property. Petrol earns its place on acreage, long driveways and heavy tree cover, where you need to keep going long after a battery has given up.
Two things to know before you order it: it runs at 112 dB, so hearing protection is not optional — and petrol blowers are restricted or banned in a growing number of US towns. Check your local ordinance first.
Three things a spec sheet will not tell you
Whether the CFM figure is measured at the tube. Some manufacturers quote airflow at the housing, before the nozzle narrows it. The number you care about is at the end you are holding.
How long it runs at that figure. Peak CFM on turbo is not the same as sustained CFM for forty minutes. This is why two batteries and two chargers matter more than another fifty CFM.
What it weighs on your arm at minute twenty. Handheld blowers are all comfortable in a shop. The honest comparison is after half an hour with your elbow out.
Straight talk about what a blower is not
A leaf blower moves loose material. It does not lift leaves that have started to rot into the grass, and it will not clear a lawn that has been left since last autumn — that is a job for a rake and a scarifier, and no amount of CFM changes it.
It is also not a vacuum or a mulcher. If you want the leaves collected and shredded rather than moved to a corner, you want a different machine, and we would rather say so than sell you the wrong one.
The one habit that halves the work
Work with the wind, not across it, and always toward one corner. Most people wander, push leaves in three directions, and end up rounding up the same pile twice.
And go earlier than feels necessary. Leaves that have been down two days move in one pass. Leaves that have been down two weeks and had rain on them are a different job entirely — which is the real argument for owning a blower rather than borrowing one.
Read the CFM, not the MPH.
Both of our blowers are on the leaf blowers page, with the honest limits of each written on the product page. If you want the cordless one, it is the 40V 680 CFM blower — free US shipping and thirty days to change your mind.