BMR Calculator

How BMR Calculator works

Calculate basal metabolic rate and daily calorie needs at five activity levels. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

The equation

Basal metabolic rate is estimated with Mifflin–St Jeor: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, and − 161 for women. It estimates the energy your body uses at complete rest, before any movement at all.

For a 28-year-old man at 70 kg and 175 cm, that is about 1,685 kcal a day. A woman of the same age and size lands around 1,519 kcal, because the constant differs by 166.

From resting to real life

Nobody stays at rest. Multiplying BMR by an activity factor gives total daily energy expenditure, which is the number that actually matters for eating:

Why the number can be wrong for you

The equation predicts a population average from four inputs. Muscle mass, thyroid function, medication, sleep debt and years of dieting all move actual expenditure, sometimes by several hundred calories a day.

Use it as a starting estimate for two weeks, then adjust against measured weight change. That feedback loop beats any formula, and it costs nothing but patience.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions

How this number is produced

The calculation is Mifflin–St Jeor: 10 × kg + 6.25 × cm − 5 × age, +5 for men and −161 for women, following Mifflin & St Jeor, 1990. The formula is repeated here so the result can be checked by hand rather than taken on trust.

This is a calculator, not advice. No clinician, accountant or adviser has reviewed it, and it cannot see your circumstances. For anything involving health, a loan, a tax filing or a religious obligation, confirm the figure with a qualified professional or the authority that publishes the rule.