BMR & Daily Calorie Calculator
Estimate adult BMR and daily maintenance calories.
Estimate adult daily calories
Your estimate
Estimated maintenance calories
- Basal metabolic rate (BMR)
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- Activity level
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- Activity multiplier
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Educational estimate for adults only. It is not a diagnosis, a nutrition prescription, or a substitute for advice from a qualified healthcare professional.
Your entries and results stay in this browser. This tool does not send, save, or add them to the page address.
How to use this calculator
Choose metric or US units, select which published constant set to apply, then enter your age, weight, height, and the activity level that best matches a typical week. The result reports an estimated basal metabolic rate and an estimated daily maintenance figure.
If your activity varies week to week, try more than one activity level. The range between them is often more informative than any single number.
BMR compared with maintenance calories
Basal metabolic rate estimates the energy used at complete rest. It reflects the ongoing work of staying alive rather than anything you consciously do.
Maintenance calories multiply that resting figure by an activity factor to approximate a full day, including walking, working, chores, and exercise. The activity factor is the least precise part of the calculation, because it compresses widely varying behaviour into one number.
The five activity multipliers are conventional planning heuristics in wide use. They are separate from the Mifflin-St Jeor resting-energy equation described below and were not established by that study, which measured resting expenditure only. No source is claimed for them here, because none would be honest: they are a convention, not a measurement, and they should not be read as an observed individual energy expenditure.
Why individual needs vary
The Mifflin-St Jeor equation was derived from population data, and it estimates RESTING energy expenditure – the basal figure – and nothing beyond it. It cannot observe body composition, and two people at the same height, weight, and age can have different amounts of muscle and therefore different resting needs. The maintenance number carries that uncertainty plus the activity multiplier’s, so it is the looser of the two estimates.
Energy needs also change with pregnancy, breastfeeding, growth, illness, injury and recovery, thyroid and other hormonal conditions, some medications, some disabilities and mobility differences, and sustained athletic training. This calculator does not model any of those situations.
Reading the result responsibly
Treat both numbers as starting estimates rather than targets. This tool does not recommend a calorie intake, a deficit, a surplus, or any change to what you eat, and it is not intended for children or teenagers.
If you are making decisions about nutrition, weight, training, or a health condition, or if you are pregnant, breastfeeding, managing an eating disorder, or living with a chronic condition, speak with a qualified healthcare professional or registered dietitian who can account for your full situation.
Frequently asked questions
What is the difference between BMR and maintenance calories?
Basal metabolic rate estimates the energy your body uses at complete rest for functions such as breathing, circulation, and temperature regulation. Maintenance calories multiply that figure by an activity factor to estimate the total energy used across a typical day, including movement and exercise.
Which equation does this calculator use?
It uses the Mifflin-St Jeor equation, which estimates BMR from weight in kilograms, height in centimeters, and age in years, with one of two published constant sets. US measurements are converted to kilograms and centimeters first using exact conversion factors.
Why does the calculator ask for female or male constants?
The published Mifflin-St Jeor equation defines exactly two constant sets, labeled female and male in the original research. The selection chooses which published constants to apply. It is a formula input, and no single equation describes every body.
How accurate is a calorie estimate like this?
It is an approximation from a population-level equation. Real energy needs vary with body composition, genetics, hormones, medications, health conditions, sleep, environment, and the accuracy of your own activity estimate. Two people with identical inputs can have meaningfully different needs.
Is this calculator appropriate for everyone?
No. It applies standard adult equations and is not intended for children or teenagers, whose needs are assessed differently. Pregnancy, breastfeeding, illness, recovery, some medications, some disabilities, and intensive athletic training can all change energy needs in ways this estimate does not capture.