Four questions, four calculators

All free, none need an account, and every one runs entirely in your browser — nothing you type is sent anywhere. Each publishes the arithmetic it uses.

Free·No account·Nothing leaves your browser
How much of my weight loss is muscle? Start here Estimates the lean share of what you have already lost from your weight, protein, training and age — then names the one thing worth changing first. Muscle check · Seven questions · about 60 seconds How much protein do I need? Your daily target and the range around it, from the clinical nutrition guidelines for protecting muscle in a deficit — with the food that gets you there. Protein calculator · Two questions · about 20 seconds How much weight do people actually lose? What the STEP-1 and SURMOUNT-1 populations did, against your own starting weight — the average, and how many people reached each result. Weight loss calculator · Published trial data · no modelling What does my scan actually say? Most exact If you have two readings from a DEXA or a smart scale, this works out exactly what share of your loss was lean tissue. No estimating at all. Body composition calculator · Needs two readings

Which one do I want?

If you are not sure, start with the muscle check — it is the one that answers the question most people arrive with, and it points at whichever of the others is relevant to you.

If you already have a DEXA report or a smart scale with two readings on it, skip straight to the body composition calculator. It measures rather than estimates, and where the two disagree, that one is right.

They agree with each other, and that is tested

The protein target shown on the protein calculator is produced by the same code as the one inside the muscle check. A test in the build runs both over thousands of weights and ages and fails if they ever print different numbers for the same person — because a calculator that contradicts itself is worse than no calculator.

Every formula, threshold and source is on How we work.

What none of them are

They are estimates and arithmetic, not diagnoses. Nothing here is medical advice and nothing here is a medical device. None of them will ever tell you to start, stop, change or pause a medication or a dose. That is a conversation with your prescriber. Two people who enter identical numbers can have genuinely different bodies. Where we do not know something, we say so rather than filling the gap.