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Surplus, sized correctly

Bulking Calculator

Set a calorie surplus that builds muscle without an avoidable layer of fat — with monthly gain projections and a protein target.

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WHO guideline: 150 min/week minimum · 300 for full benefits.

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Why small surpluses win

Muscle protein synthesis has a speed limit. Beyond a modest surplus, extra calories don't become extra muscle — they become fat that a future cut has to remove. For most natural lifters past the beginner stage, +200–300 kcal/day supports close to maximal muscle gain (~0.25–0.5% of body weight per month) at a fraction of the fat cost of old-school bulking.

The other two-thirds of the equation

Frequently asked questions

How many calories should I eat to bulk?

TDEE plus 200–300 kcal covers most lifters — typically 2,700–3,300 kcal for men and 2,200–2,700 for women, depending on size and training volume. The calculator personalizes it.

Can I build muscle without a surplus?

Beginners, returning lifters and people with higher body fat often can ('recomposition'). Trained, lean lifters generally need at least a small surplus for meaningful gains.

How fast should I gain on a bulk?

Roughly 0.25–0.5% of body weight per month for experienced lifters, up to ~1% for beginners. Faster than that and the extra is mostly fat.

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Sources

  1. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. Br J Sports Med. 2018. [link]
  2. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014. [link]
Medical disclaimer: CaloriesKit provides educational estimates only and is not medical, nutritional, or fitness advice. Calculators use population-level formulas that may not reflect your individual needs. Consult a physician or registered dietitian before changing your diet or exercise routine, especially if you have a medical condition, are pregnant, or are under 18.