Free calculators
Free Nutrition & Fitness Calculators
Simple, accurate calculators for everything that drives your nutrition — your maintenance calories, macro split, basal metabolic rate, deficit, and protein target.
Each one is free, instant, and built on the same formulas trainers and dietitians use. When you're ready to stop doing the math by hand, WhispCal tracks it all automatically.
By Thomas MoriceBuilds WhispCal, and writes everything here
All calculators
Which calculator do you need?
The five answer different parts of one chain. Your basal rate is what you burn doing nothing. Multiply it by how much you move and you get your maintenance. Cut below that and you lose weight; split what is left between fat, carbs and protein and you have a daily plan.
If you only run one, run the TDEE calculator. Every other number on this page is derived from it.
- BMR calculator — what your body spends staying alive, the floor the rest is built on
- TDEE calculator — your basal rate plus movement and training, which is the number a target comes from
- Calorie deficit calculator — how large a cut gives the rate of loss you actually want
- Macro calculator — how to divide those calories between fat, carbs and protein
- Protein calculator — grams per day, the one macro worth fixing before the others
How accurate is a calorie calculator?
Every calculator here uses the Mifflin-St Jeor equation, which research consistently ranks as the most accurate for the general population. Accurate is a relative word. For any single person the result carries an error of roughly 10% in either direction, and the activity multiplier on top of it is a guess you make about your own week.
Two people with the same height, weight, age and sex can burn several hundred calories a day apart. That is not an argument against calculating. It is an argument for treating the answer as a hypothesis you test, rather than a number you obey.
The true figure also moves while you use it. Diet for long enough and adaptive thermogenesis quietly lowers it, so the deficit you set in week one is smaller by week six.
What to do with the number once you have it
Take the target, eat it for two to three weeks, and weigh yourself often enough to see a trend rather than a reading. If your weight moves at the rate you planned, the estimate was close enough. If it does not, the estimate was wrong and the scale is the correction.
- Losing fat: 300 to 500 kcal below maintenance, which is roughly 0.25 to 0.5 kg a week
- Holding weight: eat at maintenance, and expect the number to drift as your weight and training change
- Building muscle: 200 to 300 kcal above maintenance, slowly, because faster is mostly fat
When a calculator stops being enough
A calculator reads your height, weight, age and sex. It cannot see the one thing that decides your result, which is how your body responded to what you actually ate.
That is the job WhispCal does. It compares what you log against your weight trend over weeks, works out the burn your body is really running at, and moves your target when the two disagree. No recalculating, and no guessing at an activity multiplier twice a year.
Frequently asked questions
Which formula do these calculators use?
Mifflin-St Jeor for your basal rate, then an activity factor between 1.2 for a desk job with little exercise and 1.9 for twice-daily training or physical work. It is the equation most often recommended over the older Harris-Benedict, because it tests closer on modern populations.
How often should I recalculate?
Whenever your weight has changed by about 5%, or whenever progress has stalled for two weeks at a target you were actually hitting. Both mean the inputs the calculator used are out of date.
Why does my calculator number differ from my watch?
A watch estimates from heart rate and movement, a calculator estimates from your body size and a self-reported activity level. They are two guesses built from different evidence, so they rarely agree. Neither is measured. Your weight trend over a few weeks is.
Are these calculators free?
Yes. All five are free, need no account, and give you the number in the page. Nothing is emailed to you and nothing is held back.
Let WhispCal do the math automatically
These numbers are a starting point. WhispCal measures how your body actually responds — logging food in 3 seconds by voice, photo, or barcode — and auto-adjusts your targets as your metabolism changes. Free on iOS and Android.
Free on iOS & Android