Calculators
22 calculators, no sign-up.
Every one runs in your browser — nothing is typed into a server, because there is no server. Each page names the equation it uses and says where it stops being reliable, which is the part most calculators leave out.
Energy
What you burn, and what moving burns on top of it.
Calorie deficit
What to eat each day to lose weight, how big the deficit has to be, and the date you would get there.
Maintenance calories
The amount you can eat without gaining or losing weight, from Mifflin–St Jeor and an activity factor.
BMR
The energy your body spends doing nothing at all, across three equations so you can see them disagree.
Calories burned walking
What a walk actually costs, gross and net of the resting energy you would have spent anyway.
Calories burned running
Per kilometre and per session, by pace and by weight, with the incline accounted for.
Calories burned cycling
Rides cost less than most calculators claim. Here is the figure by speed and weight.
Steps to calories
Convert a step count into energy using your own stride, not a flat 0.04 kcal a step.
Calories to kilojoules
kcal to kJ and back, for labels in Australia, New Zealand and the EU.
Body
Measurements, ratios and what they are and are not good for.
BMI
Body mass index with the WHO bands, the lower Asian cut-offs, and a plain account of what it misses.
Body fat percentage
The US Navy tape method, with the error bars stated rather than hidden.
Lean body mass
What you weigh without the fat, across the Boer, James and Hume equations.
Ideal weight
Devine, Robinson, Miller and Hamwi — four answers, and why a healthy BMI range beats all four.
Waist-to-height ratio
The measurement NICE now recommends alongside BMI, and the boundary that matters.
Waist-to-hip ratio
Where you carry it, against the WHO cut-offs for men and women.
Food
Turning a calorie target into grams on a plate.
Macros
Protein, carbs and fat in grams from a calorie target, with protein set first.
Protein intake
How much protein a day, by bodyweight and by whether you are in a deficit.
Carb intake
Carbohydrate grams a day, as the remainder after protein and fat are set.
Fat intake
Daily fat in grams, and the floor you should not cut below.
Water intake
How much to drink a day, counting what food already gives you.
Planning
Deciding the pace, and what happens when you stop.
Why these disagree with other calculators
Put the same height, weight and age into five sites and you will get five answers. That is not a bug in any of them — it is that resting metabolic rate has to be estimated, and the equations were fitted to different people in different decades. Mifflin–St Jeor came from 498 adults in 1990. Harris–Benedict came from 239 people in 1919 and runs high by about 5%. Katch–McArdle ignores height entirely and asks for body fat instead.
Every calculator here names the equation it uses, and where several are in circulation it shows you all of them rather than picking one and hiding the choice. Why calculators disagree goes through it properly.
What a calculator cannot do
A number worked out today is already stale tomorrow. Your maintenance falls as you get lighter, incidental movement drops during a deficit, and the 7,700 kcal per kilogram conversion is an average rather than a constant. Treat any target date as a projection.
Caldown exists for that part: it turns the goal into a countdown that ticks down live from Apple Health and recomputes the finish date from your real average deficit, not the figure you typed at the start.