Calorie Surplus Calculator
Building muscle takes a calorie surplus, but too big a surplus mostly adds fat. Get a daily target and a weekly gain goal that match your lifting experience.
Your details
Your results
Enter your maintenance calories and your weight.
Daily calories to build muscle
kcal a day
A surplus of . Aim to gain a week.
| If you gain | Then |
|---|---|
| Less than a week | Eat a bit more |
| a week | Keep going |
| More than a week | Eat a bit less |
How to use it
- Enter your maintenance calories. Don't know them? Get them from the TDEE Calculator first.
- Enter your current weight and pick your lifting experience.
- Eat at the target for 2 to 4 weeks, weighing yourself several times a week.
- Compare your average weekly gain with the target and adjust, using the table under the result.
How it's calculated
The targets. From a 2019 review of nutrition for natural bodybuilders in the off-season (Iraki, Fitschen, Espinar & Helms):
| Experience | Calorie surplus | Weekly weight gain |
|---|---|---|
| Up to a few years | 10–20% above maintenance | 0.25–0.5% of bodyweight |
| Advanced | Low end: about 10% | About 0.25% of bodyweight |
Daily target = maintenance × (1 + surplus %), rounded to the nearest 10 kcal.
Example: with maintenance at 2,600 kcal and a 10–20% surplus, aim for 2,860 to 3,120 kcal a day. At 75 kg, a 0.25–0.5% weekly gain is about 0.19 to 0.38 kg.
Why use percentages, not 7,700 kcal per kg? When you build muscle, part of the weight you gain is muscle and water, which hold far less energy than fat. The 7,700 kcal rule is made for fat loss, so it’s a poor fit here. The review instead gives the surplus as a share of maintenance and the gain as a share of bodyweight.
Adjust as you go. The review advises starting with a target, then adjusting based on how fast you actually gain. Use your weekly average weight, not a single weigh-in.
Sources
Questions
How big should my calorie surplus be?
About 10 to 20% above maintenance, according to a 2019 review of muscle-building nutrition. Advanced lifters gain muscle more slowly, so they should stay at the low end.
How fast should I gain weight?
About 0.25 to 0.5% of your bodyweight a week if you've been lifting up to a few years; around 0.25% if you're advanced. For a 75 kg lifter, that's roughly 0.2 to 0.4 kg a week.
Why not just eat as much as possible?
Your body can only build muscle so fast. Beyond that, extra calories are stored as fat, which you'll later have to diet off.
How do I know if it's working?
Weigh yourself several times a week and compare weekly averages, which smooths out daily swings from water and food. Track your lifts too; strength going up is a good sign the weight is muscle.
Updated November 9, 2026.