Calorie Calculator
Daily energy needs from the Mifflin–St Jeor equation.
Runs entirely in your browser — nothing you enter is uploaded or sent to a server.
These are estimates from an equation fitted to a population, not a measurement of you — individual results commonly land about 10% either side, and further out at the extremes of build or age. The tool shows maintenance energy only and deliberately offers no weight-loss or weight-gain targets; setting one is a decision to make with a doctor or a dietitian, not with a web page. Read our full disclaimer.
About this tool
This calculator estimates two related numbers. The first is your basal metabolic rate — the energy your body uses lying still and doing nothing, which is most of what you burn in a day. The second is total daily energy expenditure: the BMR figure multiplied by an activity factor to account for moving around and training. It uses the Mifflin–St Jeor equation, published in 1990 and the one most current guidance prefers over the older Harris–Benedict formula, because it predicts measured resting rates more closely across a general adult population. Rather than making you pick one activity level and hiding the rest, the tool shows the whole table, which is the honest way to present a set of multipliers that were never precise to begin with.
Example
A 30-year-old male, 80 kg and 180 cm, has a BMR of 1,780 kcal. At a moderately active level (×1.55) that works out to about 2,759 kcal a day.
How to use
- 1Pick metric or imperial units.
- 2Choose which form of the equation to use — it differs by a fixed constant between the male and female versions.
- 3Enter your age, weight and height.
- 4Read your BMR, then the daily figure at whichever activity level matches your week.
Features
- Mifflin–St Jeor equation, the current standard for resting metabolic rate.
- The full activity table rather than a single figure — sedentary through to extremely active.
- Metric or imperial input.
- Maintenance energy only: no goal targets, no deficits, no advice.
Frequently asked questions
What is the difference between BMR and daily calories?
BMR is what your body uses at complete rest — breathing, circulation, keeping your temperature up. It's typically 60–70% of the total. The daily figure multiplies that by an activity factor to cover everything else you do, from walking to the kitchen to a two-hour training session.
Why does the calculator use Mifflin–St Jeor rather than Harris–Benedict?
Harris–Benedict came first, in 1919, and was revised in 1984. Mifflin–St Jeor was published in 1990 against a more representative modern sample and predicts measured resting rates more accurately for most adults, which is why current dietetic guidance generally prefers it. Both are regressions, and both carry real error for any individual.
How accurate is this for me specifically?
Treat it as a starting estimate, not a measurement. Validation studies put the equation within about 10% of measured resting rate for most people, but individuals sit outside that, and the activity multipliers are coarse — the gap between 'lightly' and 'moderately' active is a judgement call, and it's worth several hundred calories.
Why doesn't it tell me how much to eat to lose weight?
Because that's dietary advice, and we're a calculator. Adjusting energy intake interacts with your health history, medication, training and a lot else that a web form can't see. We show what the equation produces — the energy it estimates you use — and leave the decision about what to do with that to you and a professional.
Does the male/female choice mean anything beyond the formula?
No. In the Mifflin–St Jeor equation the only difference between the two forms is a constant: +5 for the male version and −161 for the female one, a fixed 166 kcal gap. It reflects average differences in body composition in the sample the equation was fitted to. Pick whichever gives you the more useful reference point.
More health tools
View allBody Fat Calculator
Estimate your body-fat percentage using the US Navy circumference method, with fat and lean mass in kilograms. Nothing you measure leaves your browser.
Open toolMacro Calculator
Convert a daily calorie figure and a macronutrient split into grams of protein, carbohydrate and fat, with the calories each one accounts for. Free and client-side.
Open toolWater Intake Calculator
Estimate daily fluid intake from body weight and exercise, shown as a range in litres, millilitres and cups — because the underlying rule of thumb isn't precise enough for a single number.
Open tool