Methods and Sources

Daily Calorie Needs

The daily calorie calculator works in three steps.

1. Basal Metabolic Rate: Mifflin-St Jeor

Basal metabolic rate (BMR) is the energy your body uses at complete rest. We estimate it with the Mifflin-St Jeor equation, published in 1990 and found in later reviews to be the most accurate of the common equations for healthy adults.

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

The equation was built from adults aged 19 to 78, so the calculator accepts ages 18 to 80. It does not account for body composition, so very muscular people may need more than it predicts and people with more body fat may need less.

2. Activity Multiplier

We multiply BMR by an activity factor to estimate total daily energy expenditure, the calories you burn in a normal day. These multipliers are widely used estimates, not measurements, and choosing the wrong level is the most common source of error.

Activity level	Multiplier
Mostly sitting, little exercise	1.2
Light: 1 to 3 workouts a week	1.375
Moderate: 3 to 5 workouts a week	1.55
Very active: 6 to 7 hard workouts	1.725
Extra active: physical job plus training	1.9

3. Goal Adjustment

To lose or gain weight, we subtract or add calories using the rule that about 3,500 calories equals one pound of body weight (about 7,700 calories per kilogram). This rule works for short-term planning but overstates long-term loss, because the body burns less energy as weight comes off. Expect progress to slow over time.

We never show a target below 1,200 calories a day for women or 1,500 for men. These are common minimums in weight-loss guidance. If a chosen pace would go lower, the calculator holds the target at the minimum and suggests a slower pace.

Starting Macro Split

The macro split sets protein at 1.6 grams per kilogram of body weight, fat at 30% of calories and carbohydrates as the remainder. 1.6 g/kg reflects meta-analysis findings on protein and muscle retention, and 30% fat sits inside the 20% to 35% range in U.S. dietary guidance. Treat the split as a starting point, not a prescription.

Calories Burned

Our calories burned calculators use metabolic equivalents (METs). One MET is the energy you use sitting quietly, defined as about 1 calorie per kilogram of body weight per hour.

Calories burned = MET × weight in kg × hours

MET values come from the 2024 Adult Compendium of Physical Activities, the standard reference that assigns an energy cost to more than 1,000 activities. Each result names the Compendium code it uses. We also show calories above sitting still, calculated with MET minus 1, because that is the better number to add to a daily calorie budget.

Compendium values are averages for adults. Fitness, technique, terrain, temperature and body composition can move the real number up or down by a meaningful amount.

Steps to Miles

The steps to miles calculator estimates stride length as 41.5% of your height, a widely used rule of thumb for walking. Real strides vary with speed, leg length and terrain, and running strides are much longer. For the most accurate result, measure your stride and enter it directly.

What We Do Not Claim

• Our calculators have not been reviewed by a physician or registered dietitian. If that changes, we will name the reviewer here.
• No calculator can replace a measurement. A lab test of resting metabolism is more accurate than any equation.
• Results are for healthy adults. See our medical disclaimer.

Sources

These are the studies and references behind our formulas.

• Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241 to 247.
• Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association. 2005;105(5):775 to 789.
• Hall KD. What is the required energy deficit per unit weight loss? International Journal of Obesity. 2008;32(3):573 to 576.
• Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52(6):376 to 384.
• Herrmann SD, Willis EA, Ainsworth BE, et al. 2024 Adult Compendium of Physical Activities: A third update of the energy costs of human activities. Journal of Sport and Health Science. 2024;13(1):6 to 12. Read the study
• U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020 to 2025.

Corrections

If you think a number is wrong, tell us. We check every report and update this page when a formula or source changes.