Calorie and nutrition calculators
What your body burns, what to eat to maintain, lose or gain at a safe pace, and how to split it into protein, carbohydrate and fat. Every target here carries its error band and is capped by safety rails written into the code.
15 calculators
Calorie Surplus Calculator
Plan a lean-gain calorie surplus with the rails built in: the weekly rate capped at 0.5% of bodyweight, the surplus at 20% of maintenance, protein included.
TDEE Calculator
Calculate total daily energy expenditure from Mifflin–St Jeor BMR and your activity level, with the honest ±10–15% error band no one else shows you.
BMR Calculator
Work out basal metabolic rate with Mifflin–St Jeor, Harris–Benedict, Katch–McArdle, Cunningham and Owen side by side, with the spread between them stated.
Calorie Deficit Calculator
Plan a weight-loss calorie target with built-in safety rails: capped at 1% of bodyweight weekly, never below 80% of TDEE or the 1,200/1,500 kcal floors.
Macro Calculator
Turn your calories into daily protein, carbohydrate and fat targets in grams: protein set per kilogram of bodyweight, fat floored for hormones.
Protein Intake Calculator
Daily protein in grams from the RDA floor of 0.8 up to 2.2 g per kilogram, with an older-adult tier, per-meal splits and a target from lean mass.
Water Intake Calculator
Your daily fluid estimate in litres, US cups or UK pints, set beside the EFSA and Institute of Medicine reference intakes, with honest, sourced caveats.
Weight Loss Time Calculator
See weeks to a goal at 0.25, 0.5, 0.75 and 1% of bodyweight a week, after the same calorie floors as the deficit tool. No crash-diet date is printed.
Weight Loss Check-In Calculator
Compare expected kilograms from (TDEE minus intake) times days over 7,700 with the scale, then hold, relog, take a diet break, or slow down.
Reverse Diet Calculator
Raise daily calories 50, 100 or 150 kcal a week from your current intake up to estimated TDEE, with a week-by-week table. Early scale drift is often water.
Calories in Body Fat Calculator
See days and weeks to lose a set amount of fat at 7,700 kcal per kg, the same constant as 3,500 kcal per lb. The last kilogram is slower than the first.
Metabolic Age Calculator
See the age whose BMI-22 Mifflin BMR matches yours. It is a gym-scale marketing label, not a tissue age or a medical test. Lean mass is what moves BMR.
Intermittent Fasting Calculator
Plan 14:10, 16:8, 18:6 or 5:2 around estimated TDEE. Weekly calories still rule. Fasting is meal timing, not extra fat burn. Protein must still fit.
Alcohol Calorie Calculator
See typical drink calories against estimated TDEE and a moderate walk. Weekly sittings add up faster than a Tuesday scale shows. Mixers are extra energy.
Fibre Intake Calculator
See daily fibre targets side by side: EFSA 25 g, IOM adequate intake 38/25 g, and 14 g per 1,000 kcal on your energy intake. Raise grams slowly with water.
Guides that explain these numbers
- TDEE, explained from the ground up
- How many calories should I eat?
- How much protein do you actually need?
- How to set your macros
- Metabolic adaptation and weight loss plateaus
- Heart rate zones, explained properly
- How to estimate your one rep max
- What a MET is, and how calories burned is estimated
- How long does safe weight loss take?
- How to read a weekly weigh-in
- Body recomposition versus weight loss
- Reverse dieting after a cut
- What metabolic age actually is
- Fasting windows and calories
- Alcohol and the calorie budget
Every formula on these pages is written out with its primary source on the methodology page. Results are informational. See the medical disclaimer.