How this calculator works
Shoveling energy cost depends on the mass of snow moved and how fast you move it. Snow mass is depth times area times density. Density varies widely with age, temperature and water content: dry new snow is near 60 kg per cubic metre, settled snow near 250 and very wet snow above 700. The calculator divides the mass by a shoveling rate in kilograms per minute to estimate the time, then applies a MET value for the method. The Compendium gives 5.3 METs for moderate hand shoveling, 7.5 for vigorous hand shoveling, 2.5 for walking behind a snow blower, 3.0 for a riding blower and 4.0 for raking a roof. The relaxed pace and the time estimate are the least certain parts.
Formula
Snow mass (kg) = depth (m) x area (m2) x density (kg/m3). Minutes = snow mass / shoveling rate (kg/min). kcal/min = MET x 3.5 x body mass (kg) / 200. Calories = kcal/min x minutes.
Worked example
A 50 m2 driveway with 20 cm of settled snow holds 0.2 x 50 x 250 = 2500 kg. At 20 kg/min that is 125 minutes. A moderate 80 kg shoveler uses 7.42 kcal/min, or about 928 kcal. With dry new snow at 60 kg/m3 the same driveway holds 600 kg, takes 30 minutes and costs about 223 kcal.
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Frequently asked questions
Why is the snow mass so large?
Water is heavy and snow packs a lot of it into a small volume. A cubic metre of settled snow can weigh 250 kg, and a driveway holds many cubic metres even when the depth looks modest.
Why does the time estimate look long?
It follows from the mass and the rate. If you clear a 50 m2 driveway in 30 minutes you are moving far more than 20 kg/min, or the depth or density is lower than selected. Adjust the rate to match your experience.
Is snow shoveling dangerous?
For some people, yes. Sudden strenuous exertion in cold weather is linked to cardiac events. Warm up, push rather than lift where possible, take breaks and stop if you feel chest pain, shortness of breath or dizziness.