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Bulking calorie calculator
Two numbers decide whether you gain muscle or just gain weight: how much you burn, and how far above it you eat. This calculator is aimed at healthy adults aged 18 and over who train with weights, and it estimates the first number before giving you a sensible figure for the second.
The short answer
To build muscle without much fat gain, most people should eat around 250 to 500 calories a day above maintenance while training with weights two or three times a week. That typically shows up as about 0.25 per cent of bodyweight gained weekly. The calculator below estimates maintenance from your height, weight, age and activity.
- Maintenance first, then a surplus of 250 to 500 calories
- Expect about 0.25 per cent of bodyweight gained a week
- Any calculator is an estimate; the scales are the real test
- Adjust every three to four weeks, not every day
Estimate your calories
This uses the Mifflin-St Jeor equation, the one most dietitians reach for, and then multiplies it by how active your week is. Be honest about the activity level: it is where most people overestimate.
Estimate your calories for gaining muscle
Around 2678 calories to stay the same weight
To build muscle, aim for roughly 2878 to 3028 calories a day. That is a small surplus, which should show up as about 0.19kg of weight gain a week. If the scales are climbing faster than that over a month, take a little back off.
Uses the Mifflin-St Jeor equation with a standard activity multiplier. Estimates like this are usually within a few hundred calories, so treat the number as a starting point and adjust it against your weekly weight trend. General information for healthy adults aged 18 and over, not medical advice. Nothing you type here is saved or sent anywhere.
How to check the number is right for you
Every calculator is working from averages, so treat the figure as a first guess. Your own weight trend over two to three weeks tells you what no equation can.
Step 1
Eat the number for two weeks
Keep it roughly consistent day to day rather than swinging between extremes.
Step 2
Weigh in the same way
First thing in the morning, a few times a week, and look at the average rather than any single reading.
Step 3
Compare to the target rate
About 0.25 per cent of your bodyweight a week. For a 75kg person that is roughly 190 grams.
Step 4
Adjust by 150 calories
Nothing moving after three weeks, add 150. Climbing too fast, take 150 off. Then wait another three weeks.
Filling the surplus with food that helps
A surplus made of protein and decent carbohydrates supports training. A surplus made of whatever fits mostly turns up as fat. The split matters less than people think, but protein does not.
| Nutrient | Amount | Where it comes from |
|---|---|---|
| Protein | 130-165g | Chicken, eggs, yoghurt, fish, tofu, beans |
| Carbohydrates | 350-420g | Rice, oats, potatoes, pasta, fruit, bread |
| Fat | 70-95g | Olive oil, nuts, dairy, oily fish |
Where the numbers usually go wrong
- Picking an activity level higher than your week really is
- Adding a 700 calorie surplus because faster sounds better
- Changing the number every few days based on one weigh-in
- Forgetting drinks, oils and what you eat at the weekend
- Eating the target on training days only
Why your maintenance number keeps changing
Maintenance is not a fixed property of your body. It is the sum of four things, and three of them move week to week, which is why a figure that worked in January can be 200 calories out by March.
| Component | Rough share | Does it move? |
|---|---|---|
| Resting metabolism | 60-70% | Slowly, as your bodyweight and muscle mass change |
| Daily movement and fidgeting | 15-30% | A lot, and often without you noticing |
| Digesting food | About 10% | Slightly, with how much protein you eat |
| Training itself | 5-10% | With session length and effort |
The largest single component scales with how much you weigh, so as you gain, maintenance rises with you and the surplus you started with quietly shrinks. That is the usual reason weight gain stalls after a good first month, rather than anything having gone wrong.
How much of the gain will be muscle
Nobody gains only muscle. Some fat comes with it, and the size of the surplus is the main thing deciding the ratio. A modest surplus in a trained beginner tends to split reasonably well; a large one mostly buys fat, because muscle can only be built at the speed your body can build it, however much you eat.
| Daily surplus | Weekly gain (75kg person) | Usual outcome |
|---|---|---|
| 0-100 kcal | Under 100g | Very slow, easy to mistake for no progress |
| 250-500 kcal | About 150-350g | The rate most beginners should aim for |
| 500-700 kcal | 400-600g | Faster on the scales, noticeably more of it fat |
| 1,000 kcal + | Around 1kg | Mostly fat, and harder to reverse than it was to add |
The scales alone cannot tell you which you gained, because water shifts with salt, carbohydrates and training. Waist measurements alongside weight give you a far better read: weight up and waist steady is the pattern you want.
Common questions
- How many calories should I eat to gain muscle?
- Around 200 to 350 calories above your maintenance level per day, alongside two or three weights sessions a week. For many beginners that lands somewhere between 2,400 and 3,000 calories a day, but maintenance varies enormously with size and activity.
- What is the difference between maintenance calories and TDEE?
- They are the same thing described two ways. Total daily energy expenditure is everything you burn in a day, and eating exactly that amount keeps your weight stable, which is why it is also called maintenance.
- Why do calorie calculators give me different numbers?
- They use different equations and different activity multipliers, and none of them can measure you directly. A spread of a few hundred calories between calculators is normal, which is why the weekly weight trend matters more than the starting estimate.
- Should I eat more calories on training days?
- You can, but it is not necessary. Your body does not settle up its accounts at midnight, so a steady daily intake across the week works just as well and is far easier to stick to.
- How long should a bulk last?
- Long enough to make it worthwhile, which usually means a few months rather than a few weeks. Muscle is built slowly, and a stop-start approach rarely gives training time to show anything.
References
Every figure in this guide traces to one of these documents. Open them and check.
- SACN dietary reference values for energy — Scientific Advisory Committee on Nutrition
- Composition of foods integrated dataset (CoFID) — Public Health England
- Healthy ways to gain weight — NHS
- Effect of nutritional intervention on body composition and performance in elite athletes — European Journal of Sport Science (2013), elite-athlete population
Educational information for adults aged 18 and over. It does not diagnose, treat or manage any medical condition. If you have a health condition, or symptoms that worry you, speak to a qualified clinician.