Free tools
Eleven free nutrition calculators.
Calories, macros, TDEE, BMR, BMI, body fat, protein, water, ideal weight and a deficit timeline. No sign-up, no email, no limit — and nothing you type leaves your browser, because every one of them is arithmetic running on your own device.
The eleven calculators
Calorie calculator
BMR, maintenance and a target for losing, holding or gaining — the same Mifflin–St Jeor formula the NutriLog AI app uses to build your plan.
Macro calculator
Turns a calorie target into grams, three ways: balanced, higher protein and lower carb, with the percentages shown.
TDEE calculator
What you burn in a day — printed at all five activity levels at once, because that factor is where the error lives.
BMI calculator
Your BMI, the band it falls in and the actual weight range that would put your height in the healthy band.
Protein calculator
Grams per kilogram of body weight the way the research states it, per day and per meal, in real food.
Calorie deficit calculator
How big a deficit for the rate you want, how many weeks it takes, and why the date drifts later than the arithmetic.
BMR calculator
Your BMR by three equations at once — Mifflin–St Jeor, Harris–Benedict and Katch–McArdle — so you can see how far apart they land.
Body fat calculator
Body fat percentage from a tape measure, with fat mass, lean mass and the healthy bands for your sex.
Ideal weight calculator
Four published formulas side by side, because they disagree — plus the healthy BMI range, which is more defensible.
Water intake calculator
Litres a day for your weight, training and climate, and how much of it arrives in food rather than a glass.
Macros to calories calculator
Grams of protein, carbs and fat in — calories and the percentage split out. The inversion of every other macro tool here.
Which one do you need?
- How many calories should I eat a day?Calorie calculator
- What do I burn if I change nothing?TDEE calculator
- How do I split those calories into grams?Macro calculator
- How much protein, in grams?Protein calculator
- Is my weight in a healthy range for my height?BMI calculator
- How long until I reach my goal weight?Deficit calculator
- What do I burn lying still?BMR calculator
- How much of me is fat?Body fat calculator
- What should I weigh for my height?Ideal weight calculator
- How much water should I drink?Water calculator
What a calculator cannot do
Every number on these pages is an estimate from a population equation, accurate to roughly ten per cent for most people and occasionally further out than that. None of them know your thyroid, your medication, your sleep, how much you fidget or how honestly you picked your activity level.
So the calculation is the starting point and the feedback loop is the actual method: eat to the number for two to three weeks, weigh yourself consistently, and adjust against what happened. That loop is exactly what NutriLog AI automates — it re-refines your target every time you log a weight, so the estimate converges on your real body instead of staying frozen at whatever a form said on day one.
Common questions
Are these calculators really free?
Yes. No account, no email, no usage limit and no upsell wall halfway through a result. They exist because the app already contains the arithmetic and there is no reason to hide it behind a download.
Is anything I type stored or sent anywhere?
No. Every calculation runs in your browser — there is no API call, no cookie set for it and no analytics event carrying your numbers. Close the tab and nothing survives. That is also why they keep working with a dropped connection once the page has loaded.
Which calculator should I start with?
If you want one number to eat to, start with the calorie calculator. If you know your calories and want grams, use the macro calculator. If you have a goal weight and a deadline in mind, the deficit calculator is the one that connects them.
Do these give the same numbers as the NutriLog AI app?
The calorie and macro calculators are the app’s own formula, re-implemented in the browser, and a test re-derives both sets of numbers from the same constants on every build so they cannot drift apart silently. The TDEE, BMI, protein and deficit pages go further than the app does — the app builds a plan, it does not print a BMI band.
Do I need the app to use them?
No. The app is what happens after the calculation: a one-off number is a hypothesis, and the useful part is checking it against what your weight actually does over the following weeks. The calculators are complete on their own if that is all you came for.
Eleven calculations, or one app that keeps doing them.
NutriLog AI holds the target, logs the food against it in under a minute and moves the plan as your weight data arrives. Free, no ads, Android. Free on Google Play.