BMR calculator — basal metabolic rate by Mifflin-St Jeor and Harris-Benedict (compared side-by-side).
- Runs locally
- Category Calculator
- Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.
Unlocks Katch-McArdle — the most accurate formula when you know your %.
Modern default — most accurate for the general adult population.
Older — tends to overestimate BMR by 5–10%.
Uses lean body mass — most accurate when you know body fat %.
Harris-Benedict gives a higher number than Mifflin in almost every adult — that's the documented 5–10% overestimate. Mifflin is closer to measured RMR (indirect calorimetry) in modern validation studies.
Add body fat % above to compute Katch-McArdle. If your body-fat is under ~15% (men) or ~22% (women) it is the most accurate formula available without a metabolic cart.
Using Mifflin-St Jeor — without body-fat data this is the most accurate formula.
This is BMR only — the calories you'd burn lying still for 24 h. For total daily needs add activity (TDEE).
What this tool does
Free online BMR (basal metabolic rate) calculator. Enter sex, age, height and weight in metric (cm / kg) or imperial (ft+in / lb) and we compute your BMR with three formulas side-by-side: Mifflin-St Jeor (1990 — the modern default), Harris-Benedict (1984 revision — tends to overestimate by 5–10%) and, if you provide body-fat percentage, Katch-McArdle (uses lean body mass, the most accurate formula for lean / muscular bodies). We show the difference between formulas and explain which one applies to you. Unlike a calorie / TDEE calculator, this focuses purely on BMR — the calories your body burns at rest. 100% client-side — your numbers never leave the browser.
Tool details
- Input
- Numbers
- The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
- Output
- Live result
- The result area focuses on usable output, with copy, download, or preview actions when supported.
- Privacy
- Browser-side processing
- The main tool logic does not call an external API, so inputs normally stay in the current tab.
- Save / share
- No account required
- Open the page and use it; whether results survive refresh depends on the tool.
- Performance budget
- Initial JS <= 10 KB
- No WASM budget is declared, keeping the tool quick to open on mobile.
- Best fit
- Calculator · Content Creator
- Category and role tags drive related tools, internal links, and quick fit checks.
How to use
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1. Input
Paste or drop your content into the tool panel.
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2. Process
Click the button. All processing is local in your browser.
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3. Copy / Download
Copy the result or download to disk in one click.
How BMR Calculator fits into your work
Use it for fast estimates, comparisons, and planning numbers before you make the final call.
Calculation jobs
- Getting a realistic range before a purchase, plan, workout, or schedule decision.
- Comparing scenarios by changing one input at a time.
- Turning rough assumptions into a number you can discuss.
Calculation checks
- Double-check units, dates, rates, and rounding assumptions.
- Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
- Save the inputs that produced an important result so you can reproduce it later.
Good next steps
These links move the current task into a more complete workflow.
- 1 Body Fat Calculator Body fat % calculator — 4 formulas (US Navy / BMI-based / YMCA / Jackson-Pollock) with body shape visualization. Open
- 2 TDEE Calculator TDEE calculator — BMR × activity factor, with cut/bulk calorie targets and projected weekly weight change. Open
- 3 Calorie Calculator Calorie calculator — daily calorie needs (BMR + TDEE), weight loss/gain targets, macro breakdown. Open
FAQ
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