Clean Bulk Calculator
A clean bulk lives or dies on a margin you cannot eyeball: eat roughly 200 to 300 calories a day above maintenance and most of the gain can be muscle; overshoot by a few hundred more and the extra mostly becomes fat you will diet off later. This calculator builds the whole plan in one pass, estimating your maintenance with the Mifflin St Jeor equation, adding the surplus you choose, and splitting the total into protein, carbohydrate, and fat targets, including what each meal should carry.
Per-meal targets (4 meals/day)
Estimates for planning. BMR equations predict within about 10 percent for most people, so treat the first two weeks as calibration and adjust from your actual weight trend.
Quick Answer
Key takeaways
- The surplus is added to maintenance (TDEE), not to BMR. Adding it to BMR is the most common bulking arithmetic error and underfeeds by hundreds of calories.
- Protein and fat are set per pound of body weight first; carbohydrate takes whatever calories remain, which is why training fuel rises automatically with the surplus.
- Projected gain is pure energy math (surplus x 7 / 3,500). It is a planning rate, not a promise, and the two week weigh in trend is the real feedback.
- Per meal targets turn a day of numbers into food you can plate: at 4 meals, the example plan is 45 g protein, 106 g carbs, and 18 g fat per meal.
- Quick Answer
- How the clean bulk calculator builds your plan
- The formulas, step by step
- Worked example: a 180 lb lifter on the standard surplus
- Choosing your surplus and macro style
- Clean bulk versus dirty bulk
- What competing calculators miss
- Frequently Asked Questions
- Add This Calculator to Your Website
- References
How the clean bulk calculator builds your plan
The plan is built in four steps, and the result box shows every layer so you can see where each number came from. First, the Mifflin St Jeor equation estimates your basal metabolic rate from weight, height, age, and sex. Weight is converted to kilograms and height to centimeters inside the calculation, because the equation was published in metric units. Second, BMR is multiplied by your activity factor to estimate total daily energy expenditure, your maintenance level: the intake at which your weight should hold steady.
Third, your chosen surplus is added. The three intensities are fixed calorie amounts, not percentages: 250, 300, or 500 kcal a day. Fourth, the total is split into macros. Protein and fat come from per pound settings that depend on the macro style you pick, and carbohydrate fills the remaining calories, which is deliberate: carbohydrate is the fuel for hard training, so it should absorb most of a surplus. Finally the daily totals are divided by your meals per day. If you want to compare this fixed surplus approach with percentage based paces on the same body, the bulking calories calculator lays lean, moderate, and aggressive percentage options side by side.
The formulas, step by step
The Mifflin St Jeor equation, published in 1990, is the estimator most dietitians reach for because validation studies found it predicts measured resting energy expenditure within 10 percent for more adults than the older Harris Benedict equations. That still leaves a real margin: for a predicted BMR of 1,783, your true value could plausibly sit 150 kcal either side. This is why no calculator, this one included, can hand you a finished diet. It hands you a well founded starting target and a projected rate, and your job is to compare the projection with what your scale average actually does over two to three weeks, then nudge by 100 to 200 kcal if the two disagree.
On protein, it helps to know where this tool sits against the research. The position stand of the International Society of Sports Nutrition on protein and exercise puts sufficient intake for building and maintaining muscle at 1.4 to 2.0 g per kilogram a day for most exercising people. Converted, this calculator’s balanced style at 1.0 g per pound is about 2.2 g per kilogram, slightly above that range, and the high protein style at 1.2 g per pound is about 2.6 g per kilogram. That is a deliberate bulking choice, not an error: extra protein on a surplus is insurance for lean gain, and the cost is simply fewer carbohydrate calories. The high carb style, at about 1.76 g per kilogram, sits inside the ISSN range and pushes the fuel toward training instead.
Worked example: a 180 lb lifter on the standard surplus
The calculator is pre-filled with this case, and every figure below is what it returns.
| Figure | Calculation | Result |
|---|---|---|
| BMR | 10 x 81.6 kg + 6.25 x 177.8 cm – 5 x 30 + 5 | 1,783 kcal |
| Maintenance (TDEE) | 1,783 x 1.55 | 2,763 kcal |
| Bulk target | 2,763 + 300 | 3,063 kcal/day |
| Protein (balanced) | 180 lb x 1.0 g | 180 g (720 kcal) |
| Fat (balanced) | 180 lb x 0.4 g | 72 g (648 kcal) |
| Carbohydrates | (3,063 – 720 – 648) / 4 | 424 g (1,696 kcal) |
| Macro split (P / C / F) | Shares of 3,063 kcal | 24% / 55% / 21% |
| Projected gain | 300 x 7 / 3,500 | 0.60 lb per week |
| Per meal (4 meals) | Daily grams / 4 | 45 g / 106 g / 18 g |
Read the carbohydrate bar as the design of the plan, not a leftover. On a clean bulk, protein is capped near what muscle can use and fat is held moderate, so the surplus lands mostly on carbohydrate, the macro that refills glycogen and supports training volume. If you later trim or raise calories, change carbohydrate first and leave protein alone. Readers who want to explore the carbohydrate side on its own, for training days or other goals, can run the numbers through the carbohydrate calculator as well.
Choosing your surplus and macro style
| Surplus | Projected gain | Suits |
|---|---|---|
| Conservative +250 | 0.50 lb/week | First time bulkers, and anyone who gains fat easily or wants to stay lean year round |
| Standard +300 | 0.60 lb/week | Most lifters; the classic clean bulk pace |
| Aggressive +500 | 1.00 lb/week | Hard gainers who struggle to move the scale at all, and younger lifters with high activity |
| Macro style | Protein per lb | Fat per lb | Effect at 180 lb |
|---|---|---|---|
| Balanced | 1.0 g | 0.4 g | 180 g protein, 72 g fat, carbs take the rest |
| High protein | 1.2 g | 0.35 g | 216 g protein, 63 g fat, fewer carb calories |
| High carb | 0.8 g | 0.3 g | 144 g protein, 54 g fat, maximum training fuel |
| Low fat | 1.0 g | 0.3 g | 180 g protein, 54 g fat, more room for carbs |
A note on the aggressive row: muscle building has a rate ceiling that extra food does not raise. Past a moderate surplus, the additional calories are stored mostly as fat, which is why the standard 300 kcal option is marked recommended. The aggressive setting exists for the genuine hard gainer case, where daily activity is high and even maintenance is hard to hit, not as a faster route to muscle for everyone.
Clean bulk versus dirty bulk
Clean bulk
- Surplus of 250 to 500 kcal a day
- Mostly whole, nutrient dense foods
- Gain of about 0.5 to 1 lb a week, mostly lean
- Short, mild cut needed afterward
Dirty bulk
- Surplus often 1,000 kcal a day or more
- Food quality ignored; anything calorie dense goes
- Gain of 2 lb a week or more, with a large fat share
- Long, aggressive cut that risks the muscle just built
The dirty bulk is not a strawman: it does build muscle, and for a underweight beginner it can be a pragmatic phase. The cost shows up later. Fat gained on the way up has to be dieted off, and long cuts are where strength and muscle quietly leak away. The clean approach trades a slower scale for a far better muscle to fat ratio and a cut measured in weeks rather than months. It is the mirror image of the fat loss problem handled by the carbs to lose weight calculator: in both directions, the size of the calorie gap, honestly estimated, decides the outcome more than any single food choice.
What competing calculators miss
The closest rivals get the core equation right, and several use the same Mifflin St Jeor base. Where they fall short is in what happens after the calorie total appears.
Miss 1: percentage surpluses with no fixed option. Percentage based tools (10, 15, or 20 percent of maintenance) quietly give bigger surpluses to bigger people and smaller ones to lighter lifters, even though the useful surplus range is fairly absolute. This calculator uses fixed 250, 300, and 500 kcal steps, so the plan means the same thing at any body size.
Miss 2: macros as fixed percentages. Splitting the total 30 / 40 / 30 by percentage makes protein rise and fall with calories for no physiological reason. Here protein is anchored to body weight, which is how the research expresses it, and carbohydrate absorbs the change.
Miss 3: no per meal translation. A day target of 424 g of carbohydrate is abstract until it becomes about 106 g per meal across four meals. The per meal rows are the difference between a number and a plan you can cook.
One honest limit: the activity factors are broad bands, and the jump from Moderate (1.55) to Very active (1.725) is worth about 300 kcal at this body size, as large as the surplus itself. If your step count and job activity sit between bands, pick the lower one and let the two week trend correct you.
Frequently Asked Questions
A clean bulk is a small, controlled calorie surplus, here 250 to 500 kcal a day, eaten mostly from nutrient dense foods, with the goal of gaining muscle while keeping fat gain low. It contrasts with a dirty bulk, where the surplus is large and food quality is ignored, which gains weight faster but leaves a much longer cut afterward.
Your maintenance calories (TDEE) plus your chosen surplus. For the worked example on this page, maintenance is 2,763 kcal and the standard 300 kcal surplus gives a target of 3,063 kcal a day. Start with the standard surplus unless you are a hard gainer or gain fat very easily.
This calculator sets protein by body weight and macro style: 1.0 g per pound on the balanced and low fat styles, 1.2 g per pound on high protein, and 0.8 g per pound on high carb. For reference, 1.0 g per pound is about 2.2 g per kilogram, at the top of the 1.4 to 2.0 g per kilogram range the International Society of Sports Nutrition position stand describes as sufficient for most exercising people.
The tool projects gain from energy math alone: surplus x 7 / 3,500 lb per week, so 0.50 lb at a 250 surplus, 0.60 lb at 300, and 1.00 lb at 500. A common coaching guideline is roughly 0.25 to 0.5 percent of body weight per week. Judge the plan on a two to three week average, not single weigh ins, because water and glycogen swings hide the trend.
BMR is the energy you burn at complete rest, estimated here with the Mifflin St Jeor equation. TDEE is BMR multiplied by an activity factor from 1.2 to 1.9, and it estimates everything you burn in a day. The surplus is added to TDEE, never to BMR, because BMR ignores training and daily movement entirely.
Protein and fat grams are rounded from per pound targets, carbohydrates are rounded from the calories left over, and each percentage is rounded separately. The split shown, such as 24 / 55 / 21, can therefore total 99 or 101. The gram targets are the numbers to follow; the percentages are a summary.
This calculator gives one daily target, and the simplest clean bulk holds it steady all week, because muscle repair runs on rest days too and a steady target is easier to hit consistently. Some lifters cycle higher on training days and lower on rest days while keeping the same weekly average. Either works if the weekly surplus matches the plan.
Give the target two to three weeks first. If the weekly average is flat, add about 100 to 150 kcal a day, usually as carbohydrate. If you are gaining well above the projected rate and your waist is climbing quickly, trim 100 to 200 kcal. Small adjustments beat restarting the whole plan.
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References
- Mifflin, M. D. et al. (1990). “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition, 51(2), 241-247. The original Mifflin St Jeor equation used for BMR here.
- Jäger, R. et al. (2017). “International Society of Sports Nutrition position stand: protein and exercise.” Journal of the International Society of Sports Nutrition, 14, 20. ISSN position stand: protein and exercise (PubMed). Accessed October 2026.
- Frankenfield, D., Roth-Yousey, L., and Compher, C. (2005). “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review.” Journal of the American Dietetic Association, 105(5), 775-789. The review that found Mifflin St Jeor the most reliable predictor.
- Morton, R. W. et al. (2018). “A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength.” British Journal of Sports Medicine, 52(6), 376-384. Source of the widely used protein breakpoint near 1.6 g per kilogram for training gains.
- Science Insights summary of the ISSN position stand on protein and exercise, covering the 1.4 to 2.0 g per kilogram range and per meal distribution guidance used to benchmark this calculator’s protein settings. Science Insights: ISSN position stand, protein and exercise. Accessed October 2026.