What activity level should I pick on a TDEE calculator?

Pick it from your daily steps, not from how often you go to the gym. Under 5,000 steps a day is sedentary. 5,000 to 7,499 is lightly active, 7,500 to 9,999 moderately active, 10,000 to 12,499 active, and 12,500 or more very active. If you’re torn between two levels, take the lower one and let four weeks on the scale tell you if you were wrong.

Most calculators describe their levels by workouts. One popular calculator counts “exercise 1-3 times/week” as light activity, where exercise means 15 to 30 minutes of a raised heart rate. Three 20-minute sessions is one hour out of the week’s 168. The other 167 hours decide much more of your burn, and those are the hours your steps capture.

The simple version

Your activity level is the mileage on your car over a whole week. One fast drive on Saturday barely moves it. The daily commute does.

How big a level is

Our calculators use the usual calculator scale: your resting burn times 1.2 for sedentary, then 1.375, 1.55, 1.725 and 1.9. Each level up adds 0.175 times your resting burn, about 300 calories for a 180-pound man of 40. Picking one level too high costs more than the formula’s own error, which is within 10% for about four people in five.

The words have a US definition. In the USDA calorie table behind the Dietary Guidelines, sedentary means only the activity of independent living, and moderately active adds the equal of walking about 1.5 to 3 miles a day at 3 to 4 mph. A 15-minute mile took about 1,936 steps in tests gathered by a 2011 review, so that’s roughly 2,900 to 5,800 extra steps a day. The step bands come from a 2004 review of pedometer studies, which put ordinary daily life at 5,000 to 7,499 steps.

What to do

• Look up your average daily steps over the last month on your phone or watch. Steps are a watch’s strong suit: across 56 studies, Apple Watch steps were off by about 8%, against about 28% for calories.
• Put that average into the calories from your steps calculator. Add training only where your steps miss it, like cycling, swimming or lifting.