Bodybuilding Calculators
Science-backed calculators for strength athletes and bodybuilders. No email required — all calculations run instantly in your browser.
1RM Calculator
Estimate your one-rep max from any submaximal lift
Macro Calculator
Get your daily calorie and macro targets
Body Fat Calculator
Measure body fat % using the US Navy method
Supplement Stack
Estimate your one-rep maximum from a submaximal lift. Use 3–10 reps for best accuracy.
About These Calculators
The 1RM calculator uses three validated formulas: Epley (1990), Brzycki (1993), and Lombardi (1989). For best accuracy, use a weight you can lift for 3–10 reps with good form. The resulting percentages help you structure your training zones for strength, hypertrophy, and endurance.
Based on the Mifflin-St Jeor equation, the most accurate BMR formula for most people. Protein is set at 2.2g/kg of bodyweight — the upper range supported by research for muscle building. Fat covers 25% of calories for hormonal health, with carbohydrates filling the remainder.
The US Navy circumference method is one of the most accessible and reasonably accurate body fat estimation methods, with a margin of error of ±3-4%. For best results, measure in the morning before eating, and take measurements at the same time each week to track trends.