How the calculator works
Manufacturers rate run time in different units: driveways, pounds of snow or minutes. So we put everything on one scale, the battery's energy in watt-hours, and estimate how much snow each watt-hour moves.
- The job. Your driveway plus walks in square feet, times the snow depth in inches. Twice the depth is twice the snow to move.
- Snow per watt-hour, best case. We use EGO's coverage claims, because EGO rates both its shovel and its blowers in the same unit. Its 21-inch blower is rated for a 10-car driveway under 8 inches on about 448 Wh, a 14-car driveway on 672 Wh and a 16-car driveway on 840 Wh. Counting a car space as 200 square feet, that's about 31 to 36 square-foot-inches per watt-hour; we use 33. EGO's 12-inch shovel is rated for a three-car driveway under 6 inches on 140 Wh, about 26; since most other shovels are brushed and less efficient, we use 22 for all shovels.
- Real snow. Claims assume ideal, light snow. We take about three-quarters of the best case for light powder, half for typical snow and a third for wet, heavy snow. That's the same rule of thumb we use in our battery snow blower guide.
- Cold. Lithium-ion batteries deliver less energy when cold. Batteries kept in the house lose little; batteries stored in a cold garage lose more, and more again below 0°F. See our guide to batteries in cold weather.
- The right tool. Shovels are best up to about 6 inches, single-stage blowers up to about 12, and gravel, very deep snow or a big plow ridge call for a two-stage blower.
| Factor | Value we use | Where it comes from |
|---|---|---|
| Car space on a driveway | 200 sq ft | About 10 × 20 ft |
| Blower, best case | 33 sq ft·in per Wh | EGO 21-inch coverage claims, 448–840 Wh |
| Shovel, best case | 22 sq ft·in per Wh | EGO 12-inch claim (≈26), reduced for brushed shovels |
| Light / typical / wet snow | ×0.75 / ×0.5 / ×0.33 | Our rule of thumb |
| Batteries in the house | ×1 / ×0.9 / ×0.8 | Above 20°F / 0–20°F / below 0°F, our estimate |
| Batteries in a cold garage | ×0.9 / ×0.75 / ×0.6 | Above 20°F / 0–20°F / below 0°F, our estimate |
Example: 800 sq ft driveway + 160 sq ft walks, 6 in of typical snow, 10°F, batteries indoors
960 × 6 ÷ (33 × 0.5 × 0.9) ≈ 388 Wh → two 56V 4.0Ah batteries (448 Wh) cover it, just
How to read your result
- Covers 125% or more: one charge should finish the job with margin for a heavier storm.
- Covers 100–125%: it should finish, but a wetter or deeper storm may not. A spare battery is cheap insurance.
- Covers 50–100%: plan on a second set of batteries, a recharge break or clearing in two rounds during the storm.
- Covers under 50%: the wrong tool for this job. Look at the next size up.
Clearing during the storm is the cheapest way to stretch a charge. Two rounds of 4 inches take far less energy than one round of 8 inches of settled, heavier snow, and each round fits easily on one charge.
What the calculator can't know
- Your snow. Density swings from about 5 lb per cubic foot for powder to 20 or more for wet, settled snow. The snow-type setting is the biggest single factor.
- How you clear. Pushing into deep snow at full width drains batteries faster than steady, narrower passes.
- Battery age. Older batteries hold less. Knock 10 to 20% off for packs several seasons old.
- Brands we haven't modeled. We include only kits whose battery energy we've verified and reviewed. Other brands with similar watt-hours should land in a similar range.
Want the details behind each kit? Read our EGO 21-inch snow blower review, our Snow Joe 24V-X2-SB18 review, our Westinghouse WSnow18 review, our Earthwise SN74016 review, our best cordless snow shovels guide and snow shovel vs snow blower.
Frequently asked questions
How many batteries do I need for a battery snow blower?
It depends on the area, the snow depth and how wet the snow is. As a rough guide, a two-car driveway of about 800 square feet under 6 inches of typical snow needs around 300 Wh of battery energy, which two 56V 4.0Ah batteries (about 448 Wh) cover with some margin. Under 8 inches of wet snow, the same driveway needs closer to 600 Wh, so two 6.0Ah batteries or a second set make sense.
How do you calculate battery snow blower run time?
Multiply battery volts by amp-hours to get watt-hours, the energy in the pack. Then estimate how much snow each watt-hour moves. We calibrate that from EGO's coverage claims, which rate its 21-inch blower and 12-inch shovel in driveways cleared at a given depth, and then cut the result for typical snow, wet snow and cold batteries, because manufacturer claims are best-case.
Is a cordless snow shovel enough for my driveway?
Usually only for small areas and light snow. Cordless shovels hold about 75 to 140 Wh and work best under about 6 inches of snow. A one-car driveway or a walk and steps are a good fit; a two-car driveway under several inches of snow typically needs two or three batteries, and a snow blower becomes the easier tool.
Does cold weather reduce battery snow blower run time?
Yes. Lithium-ion batteries deliver less energy when cold. The effect is temporary and smallest when batteries are stored indoors and inserted just before use. EGO's manual says its 21-inch blower may not start if the battery is at or below -4°F.
Can a battery snow blower handle a gravel driveway?
Single-stage blowers and powered shovels run their augers close to the ground and can pick up and throw stones, so they are a poor fit for gravel. A two-stage blower, which rides on skid shoes with the auger raised, is the usual choice for gravel driveways.
Sources and notes
Coverage claims for the EGO SNT2122, SNT2124 and SNT2114 blowers and the SNS1201 shovel come from their Amazon.com listings and EGO's materials, as recorded in our reviews (October 28 and November 1, 2026). Battery voltages and capacities come from each kit's listing. The −4°F starting note comes from EGO's SNT2120 operator's manual. Snow-type and cold factors, the shovel efficiency adjustment and all results are our own estimates. We did not test these products ourselves. How we research.