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Calorie Surplus Calculator

HealthMacros and Calories
About you
Units
Sex
Activity and surplus
Surplus size
Daily calories for a surplus —
Resting energy (BMR), kcal
—
Maintenance calories, kcal
—
Surplus added, kcal
—
Approximate weekly gain
—

A calorie surplus target is your maintenance intake plus a fixed daily margin. Maintenance is resting energy from the Mifflin-St Jeor equation times an activity factor. A 30-year-old man at 175 cm and 70 kg with moderate activity maintains near 2,556 kcal, so a 500 kcal surplus means about 3,056 kcal a day.

About this tool

Lifters starting a bulk, people recovering lost weight and anyone told to eat more need a number to aim for, not just advice to eat extra. This calculator estimates resting energy with the Mifflin-St Jeor equation, scales it by your activity level to get maintenance, and adds a lean, standard or custom surplus. It also shows a rough weekly gain, using the common figure of about 7,700 kcal per kilogram of body mass, and lays out every step of the arithmetic. The result is an estimate for adults: individual metabolism can differ from the equation by 10 percent or more, so the scale over two to four weeks is the real test.

How to use it

  1. Enter your body details

    Pick metric or US units, then sex, age, height and weight.

  2. Choose an activity level

    Select the description closest to a typical week, from desk job to hard daily training.

  3. Pick the surplus

    Choose lean +250, standard +500, or Custom to set a value from 100 to 1,000 kcal with the slider.

  4. Read the target

    The daily target, maintenance, resting energy and expected weekly gain update as you type.

Examples

Man, 30, 175 cm, 70 kg, +500

Units
Metric (kg, cm)
Sex
Male
Age
30
Height
175
Weight
70
Activity level
Moderate (3–5 days)
Surplus size
Standard +500 kcal

Result Daily calories for a surplus: 3,056
Resting energy (BMR), kcal: 1,649
Maintenance calories, kcal: 2,556
Surplus added, kcal: 500
Approximate weekly gain: 0.45 kg

  1. Weight = 70 kg, height = 175 cm, age = 30
  2. BMR = 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 1648.8 kcal
  3. Maintenance = 1648.8 × 1.55 = 2555.6 kcal
  4. Target = 2555.6 + 500 = 3056 kcal per day
  5. Expected gain ≈ 500 × 7 ÷ 7700 = 0.45 kg per week

Resting energy of about 1,649 kcal times the moderate factor 1.55 gives maintenance near 2,556 kcal; adding 500 puts the target at 3,056 kcal.

Woman, 25, 165 cm, 60 kg, lean bulk

Units
Metric (kg, cm)
Sex
Female
Age
25
Height
165
Weight
60
Activity level
Light (1–3 days/week)
Surplus size
Lean +250 kcal

Result Daily calories for a surplus: 2,100
Resting energy (BMR), kcal: 1,345
Maintenance calories, kcal: 1,850
Surplus added, kcal: 250
Approximate weekly gain: 0.23 kg

  1. Weight = 60 kg, height = 165 cm, age = 25
  2. BMR = 10 × 60 + 6.25 × 165 − 5 × 25 − 161 = 1345.3 kcal
  3. Maintenance = 1345.3 × 1.375 = 1849.7 kcal
  4. Target = 1849.7 + 250 = 2100 kcal per day
  5. Expected gain ≈ 250 × 7 ÷ 7700 = 0.23 kg per week

A 250 kcal surplus on a maintenance of about 1,850 kcal is a slow gain of roughly 0.23 kg a week.

How it is calculated

Target = (10 × kg + 6.25 × cm − 5 × age + s) × activity factor + surplus

s
+5 for men, −161 for women
activity factor
1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra
surplus
extra kcal per day: 250, 500 or a custom value

The Mifflin-St Jeor equation, published in 1990, predicts resting energy expenditure from weight, height, age and sex, and is among the closer predictive equations for healthy adults. Multiplying by an activity factor gives total daily energy expenditure, the intake that holds weight steady. The surplus is added on top. Weekly gain is approximated as surplus × 7 ÷ 7,700, treating 7,700 kcal as one kilogram of mixed tissue; real gain includes water and glycogen and slows as the body adapts.

Sources

When not to use it

  • Under 18, during pregnancy or while breastfeeding, energy needs follow different references.
  • When weight loss is unexplained or follows an illness, a clinician needs to assess the cause first.
  • For very muscular or very high body-fat bodies, the equation can misjudge resting energy noticeably.

Common mistakes

  • Choosing a higher activity level than a typical week supports, which inflates maintenance.
  • Judging the plan after a few days, when water and glycogen swing the scale more than tissue does.
  • Keeping the same target for months although maintenance rises as body weight increases.

Frequently asked questions

How big should a calorie surplus be for building muscle?

Many coaches use 250 to 500 kcal above maintenance. The smaller end gains more slowly with less fat; trained lifters usually sit lower because their muscle gain rate is limited, while beginners can use the upper end.

Why does the weekly gain figure use 7,700 kcal per kilogram?

About 7,700 kcal is the energy commonly attributed to one kilogram of body mass change (roughly 3,500 kcal per pound). It is an approximation: muscle tissue holds much more water and less energy than fat, so early gains can look faster.

What if my weight does not move after three weeks?

The equation may overstate or understate your real expenditure. Add 100 to 200 kcal to the daily target, hold it for two more weeks, and compare weekly average weights rather than single weigh-ins.

Is Mifflin-St Jeor better than Harris-Benedict?

Comparisons in healthy adults found Mifflin-St Jeor predicted measured resting energy within 10 percent for more people than the revised Harris-Benedict equation, which tends to run slightly high.

Does the surplus need to come from protein?

The calorie target is independent of the macro split. Protein intake of roughly 1.6 g per kg of body weight is often cited for muscle gain, with the remaining calories from carbohydrate and fat to taste.

Should the target change as I gain weight?

Yes. Every few kilograms gained raises resting energy and maintenance, so re-enter your new weight every month or so to keep the same surplus.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 15). Calorie Surplus Calculator. Tools Directory. Retrieved October 28, 2026, from https://tools.milunir.com/health/macros-and-calories/calorie-surplus-calculator/

MLA

Tools Directory Editorial Team. “Calorie Surplus Calculator.” Tools Directory, 15 Oct. 2026, https://tools.milunir.com/health/macros-and-calories/calorie-surplus-calculator/. Accessed 28 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Calorie Surplus Calculator.” Tools Directory. Last modified October 15, 2026. Accessed October 28, 2026. https://tools.milunir.com/health/macros-and-calories/calorie-surplus-calculator/.

Link<a href="https://tools.milunir.com/health/macros-and-calories/calorie-surplus-calculator/">Calorie Surplus Calculator – Tools Directory</a>