Bulking Calculator
A bulk is a phase of eating a little above maintenance so your training can build muscle. Estimate your daily calories, the surplus, your weekly gain and your macros for a lean or a faster bulk. The math runs in your browser: nothing you type is sent anywhere.
Your estimated bulking calories and macros
Fill in the form and press Calculate to see your daily calories, the surplus, the estimated weekly and monthly gain and your protein, fat and carbs.
- Daily calories
- Surplus above maintenance
- Estimated gain per week
- Estimated gain per month
- Protein
- Fat
- Carbs
- Maintenance (TDEE)
These are estimates, not medical or dietary advice. How we estimate, with sources
What is a lean bulk?
A lean bulk is a slow, planned gain: a small calorie surplus, enough protein and hard training, so that as much as possible of the weight you add is muscle. Muscle grows slowly, so eating far above maintenance mostly adds fat. A lean bulk trades speed for less fat to lose later.
How big should your surplus be?
A review of nutrition for natural bodybuilders in the off-season suggests aiming to gain about 0.25–0.5% of body weight a week for novice and intermediate lifters, and staying at the low end or below once you are advanced. This calculator's two paces are those two ends: lean, which is also the BodyMacros app's own pace, and faster, which adds more fat along with the muscle. Both are estimates.
Example: a 25-year-old man, 178 cm and 75 kg, training 4 days a week (maintenance about 2,789 kcal)
| Pace | Calories a day | Surplus (kcal) | Gain a week (kg) | Gain a month (kg) |
|---|---|---|---|---|
| Lean (0.25% a week) | 2,995 | 206 | 0.19 | 0.8 |
| Faster (0.5% a week) | 3,202 | 413 | 0.38 | 1.6 |
The same review also mentions a surplus of about 10–20% above maintenance. The lean pace comes out below that, about 7% in the example, because the calculator starts from the rate of gain. Your weight trend over a few weeks tells you which way to adjust.
Lean bulk vs dirty bulk
A dirty bulk eats whatever it takes to gain weight fast, often far above maintenance. The scale moves quickly, but the ability to add muscle is limited, so much of the extra weight is fat. A lean bulk keeps the surplus small and the food mostly the same as usual, so the cut that follows is shorter.
How fast should you gain weight?
At the lean pace, the example above gains about 0.19 kg a week, under 1 kg a month; at the faster pace, about 0.38 kg a week, or 1.6 kg a month. Weigh yourself several times a week and compare weekly averages, because daily weight swings with water and the food in your gut.
Protein, macros and what to eat on a bulk
The calculator sets protein at 1.8 g per kg of body weight, the BodyMacros app's build-muscle estimate, inside the 1.6–2.2 g per kg range on our sources page. Fat gets 30% of calories and carbs the rest. For the example at the lean pace that is 135 g of protein, 100 g of fat and 389 g of carbs, from the foods you already like. These are estimates, not a meal plan.
When to switch to a cut
There is no fixed date. Many lifters end a bulk when the fat they have gained starts to bother them, then cut back down, and the cut is shorter when the bulk was lean. Track your estimated 1RM on the main lifts as you go: if it keeps rising, the extra food is still turning into strength.
Why your bulk should be re-estimated each week
Your maintenance moves as you gain weight and as your training changes, so a surplus set once drifts. The BodyMacros app re-estimates your calorie and macro targets every week from your weight trend and the days you train, and tells you why in plain words.
FAQ
What's the difference between bulking and cutting?
Bulking is eating above maintenance to support muscle gain; cutting is eating below it to lose the fat gained along the way. Lifters often alternate the two, and in both you keep training hard and eat enough protein. This calculator estimates the bulk and the cutting calculator the cut, from the same maintenance estimate.
What can you eat on a lean bulk?
The same foods you eat now, a little more of them. Build each meal around a protein food such as meat, fish, eggs, dairy, tofu or legumes, then add the carbs and fats you like; carbs help fuel hard training. Log what you eat for a few days to see how close you get to the estimate.
How many calories should I eat to bulk?
Start from your maintenance and add enough to gain about 0.25–0.5% of body weight a week. For a 25-year-old man at 178 cm and 75 kg training 4 days a week, this calculator estimates 2,995 kcal a day at the lean pace, 206 above maintenance, and 3,202 kcal at the faster pace.
Lean bulk vs bulk: which is better?
For most lifters past their first months of training, a lean bulk. The ability to add muscle is limited, so a big surplus mostly adds fat, and a longer cut afterwards. A review on off-season nutrition suggests gaining about 0.25–0.5% of body weight a week for novice and intermediate lifters, and less once you are advanced.
How much weight should I gain per month on a lean bulk?
At 0.25–0.5% of body weight a week, a 75 kg lifter gains roughly 0.8 to 1.6 kg a month by this calculator's estimate, and advanced lifters may aim lower. Judge it from the weekly average of several weigh-ins, not from single days, because water and food make your daily weight swing.
Track this in the app
Log your food and your lifts in one place. Your estimates adjust each week to how you eat and train.
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