Calorie Calculator
This calorie calculator estimates how many calories your body needs each day for maintaining, losing, or gaining weight. Enter your age, sex, height, weight, and activity level, and the tool calculates your Basal Metabolic Rate (BMR), scales it into a maintenance calorie number, then applies a goal-based adjustment for weight loss or weight gain. The result gives you a practical daily calorie target you can use as a starting point for meal planning or food tracking. It is not a substitute for personalized guidance from a doctor or registered dietitian, particularly if you have a medical condition, are pregnant or breastfeeding, or are managing an eating disorder.
Quick answer
BMR is the number of calories your body burns at rest just to keep your organs and basic functions running.
What this tells you
- •BMR is the number of calories your body burns at rest just to keep your organs and basic functions running.
- •Multiplying BMR by an activity factor produces your maintenance calories, the amount needed to hold your current weight steady.
- •Selecting a goal (maintain, lose, or gain) applies a fixed calorie adjustment on top of your maintenance number.
- •A roughly 500 calorie daily deficit is used here as a common starting point for about 1 pound of weight loss per week.
- •A roughly 300 calorie daily surplus is used here as a modest pace for weight gain that limits excess fat gain.
- •Results are population-based estimates, not a direct measurement of your personal metabolism.
How to Use
- 1Enter your weight in kilograms and height in centimeters.
- 2Enter your age in years.
- 3Select your sex, which determines which version of the Mifflin-St Jeor equation is used.
- 4Choose the activity level that best matches your typical week, from sedentary to extra active.
- 5Pick your goal (maintain weight, lose weight, or gain weight), then calculate to see your BMR, maintenance calories, and target calories.
How It Works
Formula
BMR (Mifflin-St Jeor): Male = 10W + 6.25H - 5A + 5, Female = 10W + 6.25H - 5A - 161
Maintenance = BMR x Activity Factor
Target = Maintenance +/- Goal AdjustmentThis calculator uses the Mifflin-St Jeor equation, one of the more widely validated formulas for estimating basal metabolic rate. W is weight in kilograms, H is height in centimeters, and A is age in years. For men, the equation adds 5 at the end. For women, it subtracts 161. BMR represents the calories your body burns at complete rest, before any movement or exercise is factored in. To estimate total daily calories, BMR is multiplied by an activity factor that ranges from 1.2 for a sedentary lifestyle to 1.9 for extra active training or physical work. This produces your maintenance calories, the amount needed to keep your current weight stable. The calculator then adds or subtracts a fixed adjustment based on your chosen goal: minus 500 calories a day for weight loss, or plus 300 calories a day for weight gain, both aimed at a gradual, sustainable pace rather than a fast, aggressive one.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Maintenance estimate for an active man
BMR = (10 x 70) + (6.25 x 175) - (5 x 30) + 5 = 700 + 1093.75 - 150 + 5 = 1648.75, rounded to 1649. Maintenance = 1648.75 x 1.55 (moderate activity) = 2555.6, rounded to 2556 calories a day. Since the goal is to maintain weight, no adjustment is applied.
Weight-loss target for a lightly active woman
BMR = (10 x 60) + (6.25 x 165) - (5 x 28) - 161 = 600 + 1031.25 - 140 - 161 = 1330.25, rounded to 1330. Maintenance = 1330.25 x 1.375 (light activity) = 1829.1, rounded to 1829. The 'Lose Weight' goal subtracts 500 calories, giving a target of about 1329 calories a day.
Weight-gain target for a very active man
BMR = (10 x 85) + (6.25 x 180) - (5 x 45) + 5 = 850 + 1125 - 225 + 5 = 1755. Maintenance = 1755 x 1.725 (very active) = 3027.4, rounded to 3027. The 'Gain Weight' goal adds 300 calories, giving a target of about 3327 calories a day.
Sedentary maintenance for an older woman
BMR = (10 x 68) + (6.25 x 160) - (5 x 55) - 161 = 680 + 1000 - 275 - 161 = 1244. With a sedentary activity factor of 1.2, maintenance calories come to 1244 x 1.2 = 1492.8, rounded to 1493 calories a day. This example shows how a lower activity factor keeps the calorie target closer to BMR.
Activity level multipliers
The activity factor this calculator uses to convert BMR into maintenance calories.
| Activity Level | Multiplier | Typical Description |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise, mostly desk-based work |
| Light | 1.375 | Light exercise or sports 1 to 3 days a week |
| Moderate | 1.55 | Moderate exercise or sports 3 to 5 days a week |
| Very Active | 1.725 | Hard exercise or sports 6 to 7 days a week |
| Extra Active | 1.9 | Very hard daily training or a physically demanding job |
Choose the level that matches a typical week, not your busiest or most sedentary day.
Common mistakes
- Choosing an activity level that is too high, which inflates the calorie target beyond what daily habits support
- Confusing maintenance calories with the weight-loss or weight-gain target, which include a separate goal adjustment
- Not recalculating after a meaningful change in body weight, since BMR drops as weight decreases
- Treating the result as an exact number instead of a starting estimate to adjust from real-world tracking
- Choosing an aggressive calorie deficit for faster results instead of the gradual, sustainable pace this calculator estimates
Limitations
This calculator provides population-based estimates, not a direct measurement of your metabolism. Actual calorie needs vary with muscle mass, hormone levels, medications, genetics, and metabolic conditions that the Mifflin-St Jeor equation cannot account for. The activity multipliers are broad categories and may not match your specific routine exactly. Treat the results as a starting point and adjust based on how your weight and energy respond over several weeks.
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