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Fitness & Wellbeing

One Rep
Max

Enter the weight you lifted and how many reps you did. Get your estimated 1RM across 7 formulas plus a complete training percentage table from 50–100%.

Bench Press
Weight lifted
Unit
Reps performed: 5
5 reps
⚠️ Estimates are most accurate at 1–10 reps. Above 10, accuracy decreases significantly.
Bench Press
Estimated 1RM
117
kg · average of 7 formulas
258 lb · Epley: 117kg · Brzycki: 116kg
Training Percentages
%PurposeRepsWeight
Results by Formula
FormulaNotesEstimated 1RM

What is 1RM?

One Rep Max (1RM) is the maximum weight you can lift for a single complete repetition with proper form. It's the standard reference point for programming strength training — all percentages in structured programs are based on your 1RM for each lift.

Which formula is most accurate?

The Epley and Brzycki formulas are the most widely validated and commonly used. Epley tends to slightly overestimate at higher reps; Brzycki is considered slightly more conservative. For reps 1–5, all formulas are reasonably accurate. Above 10 reps, estimates diverge significantly.

How to use training percentages

Different % ranges target different training adaptations. 90–100% builds maximal strength (1–3 reps). 75–85% is the hypertrophy zone (6–12 reps). 60–75% builds strength-endurance (12–20 reps). 50–60% is used for technique work and warm-up. Most strength programs prescribe specific % ranges for each exercise.

Should I test my actual 1RM?

Not always — actual 1RM testing carries injury risk if performed without proper warm-up, spotting, and experience. The calculated estimate from a well-executed 3–5 rep set is safe, practical, and accurate enough for programming. Reserve actual 1RM testing for competition prep with a trained spotter.

FAQ
How do I calculate my one rep max? ▾
The simplest method: lift a weight you can handle for 3–5 reps with good form, then use a calculator. The Epley formula is weight × (1 + 0.0333 × reps). So if you bench 100kg for 5 reps: 100 × (1 + 0.0333 × 5) = 116.6kg estimated 1RM. Enter your numbers above for a full multi-formula result.
What percentage of 1RM should I train at? ▾
It depends on your goal. For strength (neural adaptation): 85–95%. For hypertrophy (muscle size): 67–85%. For muscular endurance: 50–67%. Most effective programs vary the percentage across training days and cycles. The training table above shows recommended rep ranges for each percentage automatically.
Is the 1RM calculator accurate for high reps? ▾
No — all 1RM formulas become less accurate above 10 reps. This is because high-rep sets are limited by muscular endurance as much as strength. A person who can do 20 reps at 60kg may have a different 1RM than the formula predicts compared to someone who can do 5 reps at 80kg. For best accuracy, use sets of 3–6 reps.
How often should I retest my 1RM? ▾
Recalculate whenever your training weights meaningfully change — typically every 4–8 weeks as a training block concludes. Don't test too frequently; it doesn't help and risks overuse. Many lifters recalculate at the start of each new program, or when they want to verify progress. Use this calculator after any strong training session where you hit a new rep PR.
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📈 Lift History
Each calculation is saved here so you can track your strength progress over time.
No lifts saved yet. Calculate your 1RM to start tracking.
How to Use the One Rep Max Calculator

Calculate your theoretical 1RM and get a complete training percentage table from any working set.

01
Enter your working set weight
The weight you lifted — in kg or lbs. Use a recent, successful lift where you had good form.
02
Enter your reps
How many reps you completed with that weight. The formula is most accurate for sets of 1–10 reps. Above 10 reps, the estimate becomes less reliable.
03
Choose your formula
Epley and Brzycki are the most commonly used. Epley tends to be slightly higher; Brzycki slightly conservative. The actual difference is small for most people.
04
Review your training percentages
The full table shows recommended weight for every percentage from 50% to 100% of your 1RM. Use these for programming specific training zones.
05
Use the zones for programming
Strength work: 85–95% 1RM, 1–3 reps. Hypertrophy: 65–80% 1RM, 6–12 reps. Endurance: 50–65% 1RM, 15+ reps.
💡
💡 Never test your actual 1RM without a spotter and significant training experience. Use a recent 3–5 rep set for the most accurate estimate with the lowest injury risk.