How to use the maintenance calories calculator
- Choose US or metric units and enter your age, height and weight.
- Choose the sex parameter used by the equation (see the note on limitations below).
- Pick the activity level that best describes a typical week.
- Optionally choose a different equation. Katch-McArdle needs a body fat percentage.
How the calculation works
First, the calculator estimates your basal metabolic rate (BMR), the energy your body uses at complete rest. The default is the Mifflin-St Jeor equation. A 2005 systematic review for the American Dietetic Association found that it predicted resting metabolic rate within 10% of the measured value in more healthy adults than the other common equations it compared. The revised Harris-Benedict equation is offered for comparison, and Katch-McArdle uses lean body mass instead of sex and age.
BMR is then multiplied by an activity factor from 1.2 (sedentary) to 1.9 (extra active) to estimate total daily energy expenditure, which is your maintenance calories. These multipliers are widely used conventions rather than measurements, which is a major source of uncertainty.
Formula
- W
- Weight in kilograms
- H
- Height in centimeters
- A
- Age in years
Worked examples
30-year-old female, 5 ft 6 in, 150 lb, lightly active
W = 68.04 kg, H = 167.64 cm. BMR = 680.4 + 1,047.8 − 150 − 161 = 1,417 kcal/day. × 1.375 = 1,949 kcal/day.
28-year-old male, 175 cm, 70 kg
BMR = 700 + 1,093.75 − 140 + 5 = 1,658.75 kcal/day. Moderately active (× 1.55): 2,571 kcal/day.
Assumptions and limitations
- Predictive equations estimate averages. For an individual, measured resting metabolism commonly differs by 10% or more; activity multipliers add further uncertainty.
- The sex parameter reflects the populations the equations were derived from. For people whose physiology does not match either category, results are less certain; Katch-McArdle, which uses lean mass, may be a useful comparison.
- Not intended for children, pregnant or breastfeeding people, athletes with very high muscle mass, or people with medical conditions affecting metabolism.
- This is general information, not medical or nutritional advice. A registered dietitian or doctor can give individual guidance.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the energy used at complete rest. TDEE (total daily energy expenditure) adds everything else: daily movement, exercise and digesting food. Maintenance calories are your TDEE.
Which BMR equation should I use?
For most healthy adults, Mifflin-St Jeor is a good default: in a 2005 systematic review it came within 10% of measured resting metabolic rate for more people than Harris-Benedict and the other common equations. No equation is precise for every individual. If you know your body fat percentage, Katch-McArdle is a useful comparison.
How do I check if the estimate is right for me?
Eat close to the estimate for two to four weeks while tracking your weight. If your weight trends up or down, adjust intake gradually.
Sources and references
- 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):241-247.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition. 1984;40(1):168-182.
- 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):775-789.