Choosing a Leaf Blower: CFM, MPH, and What They Mean

Leaf blower marketing leads with MPH, because a big number sounds powerful. It is the less useful of the two figures.

CFM — cubic feet per minute — is the volume of air moved, and volume is what shifts leaves. MPH is the speed that air leaves the nozzle, which helps unstick a wet leaf from paving and does very little else.

Reading the two numbers

CFM is volume. Think of it as how much air the machine can put underneath a pile of leaves to lift and move it.

MPH is velocity at the nozzle. Useful for peeling wet leaves off concrete or blasting debris out of a gutter, but a fast, thin jet of air pushes very little material.

A machine advertising 200 MPH and 300 CFM will feel fierce at the nozzle and clear a lawn slowly. One at 130 MPH and 550 CFM will move far more, far faster.

Some manufacturers quote “newtons of blowing force”, which combines the two and is a more honest single figure — around 15 N is capable, 20 N and above is powerful.

Power source

Cordless is the right default now. A brushless 40 to 80 volt machine does what a small petrol blower did five years ago, starts instantly, and is quiet enough to use without annoying the street. Buy into a battery platform you already have.

Petrol still wins on sustained high output over a large area, and on refuelling in seconds rather than waiting for a charge. The cost is noise, weight, vibration and maintenance.

Backpack units are worth it above roughly half an acre. The weight moves to your hips and shoulders rather than your arm, which changes what is comfortable for an hour of work.

Noise rules are a real constraint

Many municipalities restrict leaf blower noise, limit the hours they can be used, or ban petrol models outright — with more doing so each year. Some restrict them seasonally.

Check before buying. A petrol backpack blower that is illegal to run on your street on a Sunday morning is an expensive object.

Features that matter

• Variable speed trigger. Full power scatters mulch and gravel. Being able to modulate is more useful than peak output.
• Cruise control / speed lock. Removes the fatigue of holding a trigger for an hour.
• Brushless motor, on cordless. More power, longer runtime, longer life.
• Weight and balance. Try it held out at arm’s length, which is how you will use it.
• Flat concentrator nozzle, for wet leaves and edges.
• Round nozzle, for moving big volumes of dry leaves.

Features that matter less than the marketing suggests: turbo buttons that drain the battery in minutes, and gutter attachment kits, which are awkward and rarely used twice.

Blower, vac, or mulcher

Many machines reverse into a vacuum, drawing leaves into a bag through an impeller that shreds them — typically a 10:1 volume reduction.

That shredded material is genuinely useful: it composts far faster than whole leaves, and it makes an excellent mulch. If you were going to collect the leaves anyway, this converts a chore into a resource.

The trade-offs are real, though: the machine is heavier, the bag fills quickly, and wet leaves and small twigs clog the impeller. For large volumes over a big lawn, a lawn sweeper collects far more with less effort.

When to use a rake instead

• Wet or matted leaves — a blower barely moves them.
• Gravel, bark and mulch beds — you will redistribute the surface.
• Around delicate plants and in borders.
• Tight corners and small areas, where a rake is simply quicker.
• Early mornings, out of basic consideration.

A blower’s genuine advantage is clearing large open areas of dry leaves fast. Outside that case, the rake is often faster and always quieter — and the leaves are worth keeping either way, as leaf mould or as compost.