What is a good CFM for a leaf blower?
Awhile back I had a discussion with my neighbor about my leaf blower. He wanted to know how I decided whether my blower would be suitable for my garden. I explained that I wanted an electric leaf blower for its ease of use, maneuverability, and durability. The model I selected had the highest cfm rating I could afford, as this was important to me. Then the questions started rolling in: Why electric? What is cfm? What is a good cfm for a leaf blower?
I believe the most valuable blower is maneuverable, light, and with the highest possible cfm. CFM means cubic feet per minute. It is a measure of how much air you are throwing at the leaves in one minute. Because you are measuring a volume per minute, it also implies a speed. The question is complicated though, because when asking : What the highest possible cfm is good for a leaf blower, I mean, that several other factors weigh in on the equation. To deliver more cfm, you need more power and that normally means more weight and noise. It affects the price and therefore it is the reason that such a wide range of leaf blowers are on the market.
All manufacturers strive to extract the highest cfm from a selected power source and design. However, the speed at which it delivers the volume of air also matters. The mph rating shows how fast the air moves out of the blower. The two values, cfm and mph combined, creates the force that moves the leaves and debris. It is wrong to compare cfm to mph, and it’s equally wrong to argue the merits of cfm vs mph. You should consider both figures to understand how powerful the blower is. Both matter, that is why the suppliers quote cfm and mph.
Blowers with high cfm and high mph figures are the most effective. Leaf blowers that deliver over 500 cfm move a high volume of air and blow larger piles of leaves than the lower cfm blowers. However, you blow out small crevices more effectively with a high-speed leaf blower because it moves the air faster. Interestingly, the most powerful leaf blowers deliver huge volumes of air at moderate air speeds. A good example is one model that delivers 2530 cfm at 160 mph.
The advantages of obtaining the highest cfm are that the leaf blower blows more leaves in every pass. It also blows the leaves further and you clear the area faster. As you blow the pile of leaves along, the heap grows and a more powerful blower handles the heap better. Therefore, you clean your yard quicker and work more efficiently. It is extremely useful when you promised you will clean the yard in time for the game on television.
What is a good cfm for a leaf blower?
Unfortunately, it’s not that straightforward because cfm is not all that matters. Leaf blowers range from small handheld to large wheeled models. Their power sources include corded electric, battery-power and gas.
Handheld leaf blowers
The handheld models are the lightest, easy to move around, and fit in small spaces. A good cfm for a handheld leaf blower is from 350 to 600 cfm, combined with air speeds of over 190 mph.
The corded models range from 225 cfm at 60 mph (which I do not recommend) to 470 cfm at 270 mph. Without the battery or a gas engine, corded blowers weigh less than other handheld blowers, it makes them more comfortable to use. There is no need to stop to re-charge or re-fuel. Corded blowers are the most affordable, require almost no maintenance and they should last a lifetime.
Cordless models range from 350 cfm at 120 mph to 580 cfm at 168 mph. With the battery installed, cordless blowers weigh more than corded blowers, and the price is considerably more for a complete set. Run-times vary from 20 minutes to 60 minutes per battery. The battery-powered tools are as powerful as corded and gas powered models. Run times are comparable to gas power but they require less maintenance. Unfortunately, batteries have a limited life and replacing them can be expensive.
Gas-powered handheld leaf blowers are noisy, smelly and need special storage considerations but are easy to maneuver and have decent run times. Their cfm and mph values are similar to other handheld models because of the need to keep the weight of a handheld blower as low as possible. If not, your arms will become tired quickly.
580 to 630 is a good CFM for a backpack leaf blower.
The bigger, heavier machines, like the backpack and walk behind leaf blowers, are the most powerful and will have the highest cfm ratings. The backpack models are more suitable for a larger property with large piles of leaves. A backpack blower is still fully portable but somewhat difficult to use in confined spaces and under overhanging branches. A good CFM for a backpack leaf blower is from 580 cfm at 145 mph to 632 cfm at 180 mph. Some have claimed air speeds of 250 mph. Some backpack leaf blowers are more robust and meant for commercial use. The backpack leaf blower is the most popular model amongst owners of large properties because you can wear it for extended periods. It is versatile and you can wear it up a flight of stairs to clear the deck.
Walk behind wheeled leaf blowers
The walk-behind leaf blowers deliver the biggest punch but it’s built for a specific environment. A good CFM for a wheeled leaf blower ranges from 1080 cfm at 200 mph to 2600 cfm at 200 mph. The walk-behind model is most effective for wide-open spaces, like parks. You cannot use it on a deck, or to clear away snow or debris from the pool cover. Nor can you use it for so many other cleaning tasks that the lesser models can do. The wheeled blower requires much more work when your yard has trees, gardens, patios, and other obstructions. Pushing it around obstacles and obstructions is a lot more work. You also have little control over where the leaves blow.
Are cfm values a reliable guide?
A CFM value is not always useful when comparing blowers from competing brands. It’s because cfm is a calculated value, and the method used varies between manufacturers. We can calculate a cfm value for a handheld blower almost as high as a professional-grade backpack blower. When comparing the two, side by side, the difference becomes obvious. To avoid comparing unrealistic cfm ratings, I recommend you choose a quality trusted brand and buy the highest cfm and mph blower in their range.
Because the calculated values can mislead, researchers have attempted to compare leaf blowers in a more visual manner. Some of these methods are good at showing how blowers differ and even show the exaggerated cfm values of some blowers. Realistically, cfm and mph ratings are only a rough guide when comparing brands.
CFM is a measure of the volume of air moved by the blower in one minute. As an example, consider a blower with a rating of 512 cfm and 118 mph. Now try to imagine a volume of air in a container measuring 8 by 8 by 8 feet = 512 cubic feet. The 512 cubic feet per minute specification says the blower can move all the air out of that container, in one minute. The blower pipe may only be 3 inches in diameter so the impeller must increase the airspeed to force it through in one minute.
We can visualize that same volume of air as a 10,430.4 feet long air sausage with a diameter of 3 inches. Imagine moving this sausage within one minute through the blower and its pipe, past any point in the pipe. To displace 512 cubic feet in a minute, the sausage of air must move at a speed of 10,430.4 feet per minute, or 118.53 mph. (In this calculation I ignored all friction losses.)
The above example also illustrates why blowers have cfm and mph ratings. To move the rated volume of air (512 cubic feet) through the blower with a nominal diameter of 3 inches it must do so at a speed of 118.53 mph. To squeeze the same 512 cfm through a pipe diameter of 2 inches the sausage becomes 23,657.23 feet long. Therefore, the speed must increase to 268.83 mph. But that is only possible if the blower is powerful enough and can achieve such high speeds. Conversely, a 512 cfm blower with a 4 inch diameter pipe will only have an airspeed of 66.41 mph.
What can you use a leaf blower for?
A leaf blower, even a small handheld one, is a handy tool to have around. You will use it to clear leaves as often as needed but also to perform many other cleaning tasks. They are excellent for removing snow from the deck, pool cover, or the car in winter. during leaf free months Leaf blowers are excellent to remove dust from the interior of your car, or the load bed of a truck. I use it almost daily to remove dust and grit from the garage or workshop. Attachments are available that extend the blower pipe high enough to clear out leaves and debris from your gutters.