CALCULATOR

Lean Bulk Calculator

A surplus sized to how fast you can actually gain muscle, not how fast you would like to.

Lean bulk plan

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How fast you can actually gain muscle

The most common mistake in bulking is a surplus far larger than muscle growth can use. Muscle accrues at a limited rate, and calories beyond that rate become fat.

Realistic figures: a beginner might gain around 1 percent of bodyweight per month in the first year, an intermediate roughly half that, and an advanced lifter a quarter. For a 75 kg intermediate, that is around 0.375 kg monthly, of which perhaps half is muscle.

That translates to a surplus of roughly 250 to 400 calories, or 10 to 15 percent above maintenance. Eating 800 over does not double the muscle; it changes the composition of the weight you add.

Frequently asked questions

How big should a bulking surplus be?

10 to 15 percent above maintenance, usually 250 to 400 calories. Larger surpluses add fat without accelerating muscle gain.

How much muscle can I gain in a month?

Around 1 percent of bodyweight for beginners, roughly half that for intermediates, and a quarter for advanced lifters.

How long should a bulk last?

Four to six months minimum. Muscle gain is slow, so short bulks accomplish little.

Will I gain fat while bulking?

Some, inevitably. A moderate surplus keeps the ratio favourable.

Sources

Slater GJ et al. Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training? Frontiers in Nutrition, 2019.
Garthe I et al. Effect of nutritional intervention on body composition and performance in elite athletes. European Journal of Sport Science, 2013.
Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation. JISSN, 2014.
National Institutes of Health, Office of Dietary Supplements. Nutrient fact sheets. ods.od.nih.gov
NHS. Nutrition and health guidance. nhs.uk
US Departments of Agriculture and Health and Human Services. Dietary Guidelines for Americans, 2025-2030. dietaryguidelines.gov

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General information, not medical advice. Consult a qualified professional before changing your diet, especially with a medical condition.