One Rep Max Calculator
Estimate your 1RM for any lift from submaximal reps and weight lifted.
One Rep Max Calculator
Estimate your 1RM for any lift from submaximal reps and weight lifted.
Body Fat Percentage — U.S. Navy Method
ℹ️ For males. Female formula additionally requires hip measurement. Margin of error ≈ ±3%.
Disclaimer
Results provided by this calculator are for informational and educational purposes only. They are based on the values you enter and standard formulas, and should not be considered financial, medical, legal, or professional advice. Always consult a qualified professional before making important decisions based on these results. Roughtools makes no warranties regarding the accuracy or completeness of these calculations for your specific situation.
Frequently Asked Questions
Pro Tips
Body fat percentage, not BMI, determines whether you're overfat. Someone with 30% body fat at "normal" BMI (skinny fat) has the same metabolic risk as an overweight person.
The Navy method used here has a ±3-4% margin of error. DEXA scans are most accurate but expensive — good for periodic validation, not daily tracking.
Reducing body fat while maintaining muscle mass (recomposition) is the goal — not just weight loss. Track body fat %, not weight, to confirm you're losing fat not muscle.
Men below 6% and women below 14% body fat reach essential fat levels needed for organ function — do not target these for general health and fitness goals.
When to Use This Calculator
Measure body fat percentage at baseline before a diet and training program to track fat loss vs muscle gain.
Check body fat percentage monthly to confirm fat loss progress, especially if weight on the scale isn't changing.
Find your current body fat percentage and set a realistic target (e.g., reach athlete category for your sex).
Estimate body fat before a military, fire department, or athletic physical where body composition standards apply.
Calculate body fat alongside BMI to get a complete picture when BMI alone gives a misleading result.
About the One Rep Max Calculator
This one-rep max calculator estimates your maximum single-rep strength (1RM) for any barbell or machine exercise from a submaximal set using the Epley, Brzycki, Lander, or Lombardi formulas. Enter the weight lifted and number of reps completed to see your estimated 1RM and a full percentage chart (50–100%) for programming training sets at any intensity. Built for powerlifters, Olympic weightlifters, and anyone programming strength training.
How to Use the One Rep Max Calculator
- 1
Enter the weight you lifted (in kg or lbs).
- 2
Enter the number of reps you completed (best results with 1–10 reps; 1–5 is most accurate).
- 3
See your estimated 1RM from multiple formulas (Epley, Brzycki, etc.).
- 4
Review the full percentage chart for programming sets at 50%, 60%, 70%, 80%, 85%, 90%, 95%.
- 5
Use to set training loads for any percentage-based strength program (5/3/1, Prilepin, etc.).
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