Free tools
Free Fitness Calculators
Free calculators for training and nutrition, each built on a published formula. Estimate your VO2 max, heart rate zones and one-rep max, check your strength level for your body weight, and work out your calories, macros, BMI and body fat. Every page explains the formula, walks through a worked example and lists its sources, so you can see exactly where the number comes from.
Written by the GymStreak coaching team · Updated
Strength
Estimate your maxes and see how strong you are for your body weight.
- Strength Level CalculatorStrength standards by body weight: see how your bench, squat, deadlift and overhead press compare with your body weight, and your next milestone.Open calculator →
- One Rep Max CalculatorEstimate your 1RM from any set of 1–12 reps and get training loads for every percentage.Open calculator →
- Max Bench Press CalculatorEstimate your bench press max from a set of reps and see your bench training weights.Open calculator →
Cardio fitness
Measure your aerobic fitness and train at the right intensity.
Calories and nutrition
Work out how much you burn and how much to eat for your goal.
- TDEE CalculatorEstimate the calories you burn per day, then get a target for losing, keeping or gaining weight.Open calculator →
- BMR CalculatorEstimate the calories your body burns at rest with Mifflin-St Jeor, plus Harris-Benedict and your burn with exercise.Open calculator →
- Macro CalculatorGet daily calories and grams of protein, fat and carbs for losing fat, maintaining or building muscle.Open calculator →
Body composition
Check your BMI and estimate your body fat with a tape measure.
Army fitness
Score the Army fitness test and check the Army body fat standard.
- Army Fitness Test (AFT) CalculatorScore the Army Fitness Test, which replaced the ACFT: points for all 5 events from the official tables, with the general and combat standards.Open calculator →
- Army Body Fat CalculatorCheck the Army’s current body composition standard: waist-to-height ratio under 0.55, which replaced the tape test in July 2026.Open calculator →
How we build these calculators
Published formulas
Each calculator uses a named, published equation, such as Mifflin-St Jeor for calories, Epley and Brzycki for one-rep max, and the Cooper and Rockport tests for VO2 max. The formula and its source are on the page.
Worked examples
Every page shows the maths step by step with a real example, plus reference tables, so you can check the result yourself.
Estimates, not diagnoses
The results are estimates for fitness education and planning. They are free, run in your browser, and are not medical advice.
Turn your numbers into a training plan
GymStreak builds workouts around your goal, days and equipment, logs every set and meal, and keeps you consistent with weekly streaks.
