Calorie Surplus (Bulking) Calculator
Get a daily calorie target above maintenance sized for muscle gain, not fat gain — with the expected weekly weight change.
How big should a surplus be for a lean bulk?
Muscle grows slowly, so the surplus should be small: about 250–500 calories a day above TDEE (10–20%) for most people, toward the lower end for experienced lifters and the higher end for beginners or underweight adults. Bigger surpluses add fat faster than muscle.
Calories to gain weight per week
A 250–500-calorie daily surplus corresponds to roughly 0.25–0.5 kg (0.5–1 lb) of body weight per week on paper; real gains are often slower because some surplus is burned off. Beginners can expect around 0.5–1 kg of muscle per month; after a few years of training, a few kilograms per year is normal.
Macros in a surplus
Protein 1.4–2.0 g/kg (ISSN), fat 20–35% of calories, carbohydrate makes up the rest and fuels training. Push the extra calories mostly into carbs around workouts. The macro calculator turns the total into grams.
Bulking for beginners
Three or more resistance sessions a week with progressive overload, 7–9 hours of sleep and a modest surplus beat any “dirty bulk”. Weigh yourself 3–4 times a week and average it; if the weekly average climbs faster than 0.5 kg, trim 100–200 calories.
Sources
- ISSN Position Stand: protein and exercise, 2017 — https://pubmed.ncbi.nlm.nih.gov/28642676/
- Dietary Guidelines for Americans (current edition) — https://www.dietaryguidelines.gov/
- Mifflin-St Jeor equation — https://pubmed.ncbi.nlm.nih.gov/2305711/
This calculator is educational and not medical advice. If you have a health condition, are pregnant, or are under 18, ask a clinician before changing your diet.
What the result tells you
A daily calorie target above your maintenance, sized to your chosen pace of muscle gain.
How to use it
- Start at the leaner surplus unless you're very new or underweight.
- Weigh in weekly and adjust — gaining too fast adds fat.
- Pair it with progressive-overload training to turn calories into muscle.
Recommendations
- Aim for about 1.6–2.2 g protein per kg body weight.
- Most of the surplus should come from quality food, not junk.
- Gaining slower than expected? Add ~100 kcal; faster than ~0.5 kg/week? Trim ~100 kcal.
Health & wellbeing
A bigger surplus doesn't build muscle faster — it just adds fat. Be patient; muscle gain is slow even when everything's right.
Troubleshooting
Scale not moving? Add 100 kcal and reassess in a week. Gaining too fast? Reduce the surplus.
How it’s calculated
Maintenance calories come from Mifflin–St Jeor × activity, then a fixed surplus is added for your chosen pace.
Target = TDEE + 275 (lean), 550 (moderate), or 825 (faster) kcal/day, roughly 0.25–0.75 kg/week.
Source: Mifflin–St Jeor (1990); energy-balance principles.
Common questions
How many calories should I eat to gain weight?
TDEE plus 250–500; the calculator does the sum.
Can I gain muscle without a surplus?
Beginners and people returning from a break can, briefly ("newbie gains"); after that a surplus is needed.
How do I know if I am gaining fat?
Waist growing faster than strength; check the waist-to-hip ratio calculator monthly.