Basal Metabolic Rate (BMR) is the number of calories your body burns at rest just to maintain basic functions like breathing, circulation, and cell production. It is the minimum calories your body needs to survive.

How accurate is this calculator?

The Mifflin–St Jeor equation is considered the most accurate for estimating calorie needs, but individual results vary by 5–10%. Use this as a starting point and adjust based on your actual results over 2–4 weeks.

Should I eat below my BMR?

It is generally not recommended to eat below your BMR (usually 1,200–1,500 calories minimum). Very low calorie diets can slow metabolism, cause muscle loss, and lead to nutrient deficiencies. Consult a healthcare provider for personalized advice.

How fast can I safely lose weight?

1–2 lb per week is the commonly cited safe range for most adults. A 500-calorie daily deficit produces about 1 lb/week of loss on paper; in practice, actual loss typically tracks 0.5–1.5 lb/week and slows over time due to metabolic adaptation.

What about macronutrients (protein, carbs, fat)?

For most adults aiming to manage weight: 0.7–1g of protein per pound of bodyweight, 0.3–0.5g of fat per pound, and the rest from carbohydrates. Higher protein helps preserve muscle during a deficit and increases satiety.

Why am I not losing weight at the calculated deficit?

Common causes: underreporting food intake, overestimating activity, water retention from new exercise or sodium, or natural metabolic adaptation after several weeks of dieting. Track for at least 2–3 weeks before changing anything.

Calorie Calculator

Estimate your daily calorie needs using the Mifflin-St Jeor equation. Enter your stats and activity level to see your Basal Metabolic Rate (BMR), maintenance calories, and recommended intake for your goal. Includes suggested macronutrient breakdown.

Daily calorie needs come from two pieces: Basal Metabolic Rate (BMR) — the calories your body burns just to keep the lights on — and the additional calories burned through movement, exercise, and digestion. Add them together and you get Total Daily Energy Expenditure (TDEE), which is the maintenance calorie level where your weight stays roughly constant.

This calculator uses the Mifflin-St Jeor equation, which has been validated in clinical studies as the most accurate predictive BMR equation for the general adult population. It multiplies BMR by an activity factor to estimate TDEE, then adjusts up or down based on your goal (lose, maintain, or gain weight).

Treat the output as a starting estimate. The Mifflin-St Jeor equation is typically accurate within ±10% for an individual — close enough to set a starting target, but you'll need to adjust based on what actually happens to your weight over 2–4 weeks. Real metabolic rate varies with muscle mass, hormonal status, recent dieting history, sleep, stress, and several other factors that no formula can capture.

Inputs

Age

Gender

Weight (lbs)

Height (inches)

Activity Level

Goal

Results

Daily Target Calories

2,644 cal

Maintenance Calories

2,644 cal

Basal Metabolic Rate

1,706 cal

Goal

Maintain Weight

Recommended Macronutrients

Calorie Levels

Last updated: April 16, 2026Reviewed by the CalcMountain editorial team

Formula

Mifflin-St Jeor BMR (calories per day): Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5 Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161 Convert imperial → metric: kg = lb / 2.205 cm = in × 2.54 TDEE (maintenance calories): TDEE = BMR × Activity Factor Activity factors: Sedentary (desk job, little exercise) × 1.2 Lightly active (light exercise 1–3 days/week) × 1.375 Moderately active (moderate exercise 3–5 days/week) × 1.55 Very active (hard exercise 6–7 days/week) × 1.725 Extra active (physical job + training) × 1.9 Goal-adjusted target: Lose weight: TDEE − 500 calories/day (about 1 lb/week deficit) Maintain: TDEE Gain weight: TDEE + 300–500 calories/day (lean gain) Example: 30-year-old man, 170 lb (77.1 kg), 5'8" (172.7 cm), moderately active BMR = 10 × 77.1 + 6.25 × 172.7 − 5 × 30 + 5 = 1,705 kcal/day TDEE = 1,705 × 1.55 ≈ 2,643 kcal/day To lose 1 lb/week: ≈ 2,143 kcal/day

How to use this calculator

Enter your age in years. Metabolic rate declines slowly with age, about 1–2% per decade after 20.
Select your biological sex. The Mifflin-St Jeor formula has different constants for men and women, reflecting differences in lean body mass at the population level.
Enter your current weight in pounds.
Enter your height in inches.
Choose an activity level that honestly reflects your typical week. Most people overestimate this. "Sedentary" is the right pick for office work with no structured exercise; "moderate" requires meaningful workouts most days.
Choose a goal: lose, maintain, or gain. The calculator subtracts 500 cal/day for weight loss (about 1 lb/week) or adds 300–500 cal/day for gain.
Track your weight for 2–4 weeks at the recommended intake. If you're not losing or gaining at the expected rate, your TDEE is probably 100–300 calories different from the estimate. Adjust and continue.

Worked examples

Moderate weight loss

40-year-old woman, 165 lb, 5'6", lightly active, wants to lose weight. Weight: 165 / 2.205 = 74.8 kg Height: 66 × 2.54 = 167.6 cm BMR = 10 × 74.8 + 6.25 × 167.6 − 5 × 40 − 161 = 1,434 kcal/day TDEE = 1,434 × 1.375 ≈ 1,972 kcal/day Weight-loss target: ≈ 1,472 kcal/day A 500-calorie deficit produces about 1 lb of weight loss per week, sustained over many weeks. Most healthy adults can sustain this without major hunger if protein intake stays high.

Muscle gain

25-year-old man, 175 lb, 6'0", moderately active, wants to gain muscle. Weight: 175 / 2.205 = 79.4 kg Height: 72 × 2.54 = 182.9 cm BMR = 10 × 79.4 + 6.25 × 182.9 − 5 × 25 + 5 = 1,817 kcal/day TDEE = 1,817 × 1.55 ≈ 2,816 kcal/day Lean-gain target: ≈ 3,100–3,300 kcal/day For lean muscle gain, the surplus should be modest. Bigger surpluses just become fat. Combine with progressive resistance training and high protein intake (about 0.7–1g per pound of bodyweight).

Sedentary vs active for the same person

Same 30-year-old male, 170 lb, 5'8". BMR is 1,705 kcal/day regardless of activity. Sedentary (office, no workouts): TDEE = 1,705 × 1.2 ≈ 2,046 Moderately active (4 workouts/week): TDEE = 1,705 × 1.55 ≈ 2,643 Very active (daily hard training): TDEE = 1,705 × 1.725 ≈ 2,941 The "activity bonus" alone is roughly 900 calories/day between sedentary and very active. Most weight management progress comes from the food side, but movement creates substantial headroom.

When to use this calculator

Use this calculator to set a starting calorie target when you're beginning a weight-loss, maintenance, or muscle-gain plan. The output is most useful as a baseline for tracking — eat at the target for 2–4 weeks, weigh weekly, and adjust based on the actual rate of change rather than trusting the formula blindly.

This calculator does NOT account for: - Pregnancy or lactation (significantly higher needs; consult a clinician) - Children and adolescents (use age-specific guidelines) - Athletes with very high training volumes (the activity factors top out at 1.9, but elite endurance athletes can burn far more) - Recovery from illness, surgery, or major metabolic conditions

For weight loss specifically, the standard "3,500 calories = 1 pound" rule is a simplification. Real fat loss includes water shifts, muscle changes, and metabolic adaptation; rate of loss usually slows over time even at the same deficit. A small additional deficit may be needed every 4–8 weeks during sustained dieting.

Common mistakes to avoid

Overestimating activity level. Many people pick "moderately active" because they go to the gym twice a week — but actual data on energy expenditure suggests most adults are closer to sedentary-to-light.
Treating the calorie target as exact. The formula is ±10%. Your actual weight trend over 2–4 weeks is the ground truth.
Going too low. Diets below ~1,200 calories (women) or ~1,500 (men) cause muscle loss, hormonal disruption, and rebound binges. A moderate deficit beats a crash diet.
Ignoring protein. Protein preserves muscle during a calorie deficit, increases satiety, and has the highest thermic effect (you burn ~25% of consumed protein calories during digestion vs ~5% for fats and carbs).
Counting "exercise calories" twice. The activity multiplier already includes your workouts. Don't add an "I burned 400 calories" eat-back on top of it.
Underreporting intake. Studies consistently find that even careful tracking under-reports by 200–500 calories/day. Weigh foods on a scale rather than eyeballing portions.
Expecting linear loss. Weight fluctuates daily by 2–5 lb due to water, sodium, glycogen, and bowel content. Watch weekly averages, not daily numbers.

Frequently Asked Questions

Sources & further reading

A new predictive equation for resting energy expenditure in healthy individuals (Mifflin et al., 1990) — American Journal of Clinical Nutrition
Dietary Reference Intakes — Energy — National Academies of Sciences, Engineering, and Medicine
Adult Body Weight and Body Composition — U.S. Centers for Disease Control and Prevention
MyPlate dietary guidelines — U.S. Department of Agriculture

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