AnyTool
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How do I calculate my BMR and daily calorie needs?

Enter your sex, age, height and weight into AnyTool BMR & TDEE Calculator in metric (cm / kg) or imperial (ft·in / lb). It instantly estimates your Basal Metabolic Rate with the Mifflin-St Jeor (default), revised Harris-Benedict or Katch-McArdle equation, then multiplies it by an activity factor to show your Total Daily Energy Expenditure (TDEE) for every activity level and a calorie-goal table for losing, maintaining or gaining weight. Everything runs in your browser, so nothing is uploaded.

  • BMR = calories your body burns at complete rest
  • Mifflin-St Jeor (default), Harris-Benedict and Katch-McArdle equations
  • TDEE = BMR × activity factor (1.2 sedentary → 1.9 extra active)
  • Calorie goals: −500/−1000 to lose, maintain, +300/+500 to gain
  • 100% in your browser — no upload, no signup, works offline

What is

Basal Metabolic Rate (BMR)

Basal Metabolic Rate is the number of calories the body burns at complete rest to sustain vital functions such as breathing, circulation and cell repair. It is estimated from sex, age, height and weight with predictive equations — Mifflin-St Jeor (1990), the revised Harris-Benedict (1984) or Katch-McArdle, which uses lean body mass. Multiplying BMR by an activity factor (1.2 to 1.9) gives Total Daily Energy Expenditure (TDEE), the calories needed to maintain weight at that activity level.

Calculators

Related terms

Total Daily Energy Expenditure (TDEE)Mifflin-St Jeor equationActivity factorMaintenance calories

Frequently Asked Questions

The Mifflin-St Jeor equation is 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women.

The most accurate predictive equation, Mifflin-St Jeor, is BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years), adding 5 for men or subtracting 161 for women. AnyTool also offers the revised Harris-Benedict equation and the Katch-McArdle formula (370 + 21.6 × lean body mass in kg), and computes all three live as you type.

BMR is the calories you burn at rest; TDEE is BMR multiplied by an activity factor to include daily movement and exercise.

BMR is the energy your body needs at complete rest, while Total Daily Energy Expenditure (TDEE) adds the calories burned through daily activity and exercise. TDEE = BMR × an activity factor: about 1.2 for sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active and 1.9 extra active. Your TDEE is your maintenance calorie level, and AnyTool shows it for every activity level at once.

Eat about 500 calories below your TDEE to lose roughly 0.45 kg (1 lb) per week, or 1000 below for about 0.9 kg (2 lb) per week.

A deficit of 500 calories a day below your maintenance TDEE loses about 0.45 kg (1 lb) per week, and 1000 a day loses about 0.9 kg (2 lb) per week; to gain weight, add 300 to 500 calories. AnyTool builds this goal table from your chosen activity level and applies a safe minimum-intake floor, but it is an estimate — track your actual weight over 2–3 weeks and adjust.

Mifflin-St Jeor is the most accurate for most adults; Katch-McArdle is better if you know your body fat. Nothing is uploaded — it all runs in your browser.

The Mifflin-St Jeor equation is validated as the most accurate for most adults, the revised Harris-Benedict reads a little higher, and Katch-McArdle can be more accurate for lean or athletic bodies because it uses lean body mass from your body-fat percentage. All predictive equations are only accurate to about ±10 %. AnyTool BMR Calculator runs entirely in your browser, so your details are never sent to a server and the page works offline.

Detailed Explanation

Methodology

How the BMR & TDEE Calculator Works

AnyTool BMR Calculator estimates Basal Metabolic Rate in the browser from sex, age, height and weight using three published equations. Mifflin-St Jeor (1990, the default) is 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women. The revised Harris-Benedict (Roza & Shizgal, 1984) uses sex-specific constants, and Katch-McArdle is 370 + 21.6 × lean body mass, where lean mass = weight × (1 − body-fat%/100). The chosen BMR is then multiplied by an activity factor from 1.2 to 1.9 to produce Total Daily Energy Expenditure (TDEE), and calorie goals are a deficit or surplus on that maintenance figure. All arithmetic is pure client-side JavaScript shared through a unit-tested engine.

  • Mifflin-St Jeor: 10·kg + 6.25·cm − 5·age (+5 men / −161 women)
  • Harris-Benedict (1984 revision) and Katch-McArdle also available
  • Katch-McArdle uses lean body mass from an optional body-fat %
  • TDEE = BMR × activity factor (1.2 sedentary to 1.9 extra active)
  • All math is client-side JavaScript — no server round-trip
How It Works

Activity Levels, TDEE and Calorie Goals

Basal Metabolic Rate alone undercounts real needs, so the calculator multiplies it by standard activity factors — 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active and 1.9 extra active — and shows the resulting TDEE for every level at once. The TDEE at the selected activity level is the maintenance calorie target. From it the page builds a goal table: a 500 kcal/day deficit loses about 0.45 kg (1 lb) per week and 1000 kcal/day about 0.9 kg (2 lb) per week, while surpluses of 300 and 500 kcal support weight gain. A conservative minimum-intake floor (1500 kcal for men, 1200 for women) prevents the table from recommending an unsafe deficit.

  • Activity factors: 1.2, 1.375, 1.55, 1.725, 1.9
  • Maintenance calories = TDEE at the chosen activity level
  • −500 kcal/day ≈ −0.45 kg/week; −1000 ≈ −0.9 kg/week
  • Surplus of +300 to +500 kcal/day for weight gain
  • Deficit floored at 1500 kcal (men) / 1200 kcal (women)
Limitations

BMR Estimates Are Accurate to About ±10 %

Predictive BMR equations are population averages, so an individual’s true resting metabolism can differ by roughly ±10 % because of muscle mass, genetics, hormones, body temperature and dieting history. The activity multipliers are rougher still, and most people over-estimate their activity level. The calculator therefore frames the maintenance number as a starting point: track weight over 2–3 weeks and adjust from real results. It is general information rather than medical or nutritional advice, and the page recommends consulting a clinician or dietitian, especially during pregnancy, illness or with a history of disordered eating.

  • Predictive equations are accurate to roughly ±10 %
  • Affected by muscle mass, genetics, hormones and dieting history
  • Activity multipliers are commonly over-estimated
  • Use the result as a baseline and adjust from tracked weight
  • Not medical or nutritional advice
Privacy & Security

Privacy and Offline Use

Because all computation runs in the browser, your sex, age, height, weight and any body-fat figure are never sent to a server, there is no account or tracking, and the page works offline after first load. The calculator is built on a shared, unit-tested BMR engine so its behaviour is consistent and verifiable.

BMR & TDEE: in-browser (AnyTool) vs typical online BMR calculators
CapabilityAnyToolTypical online calculators
ProcessingRuns in your browserOften server-side
UnitsMetric and imperial, liveUsually one at a time
FormulasMifflin, Harris-Benedict, Katch-McArdleOften a single formula
TDEEEvery activity level shown at onceFrequently one level
Calorie goalsLose / maintain / gain with weekly paceOften omitted
HonestyStates ±10 % limit plainlyRarely noted
Works offlineYes (PWA)No
Cost / signupFree, no signupOften ad-heavy or gated

AnyTool computes BMR, TDEE and every goal locally and uploads nothing.