One Rep Max Calculator
Estimate your 1RM from a weight and reps
Training Percentages
| % of 1RM | Weight | ~Reps |
|---|
Free One Rep Max (1RM) Calculator
Estimate your max lift and get a full training percentage table
Your one-rep max (1RM) is the most weight you can lift for a single repetition — the number strength programs are built around. Instead of risking a true max attempt, enter a weight you lifted and how many clean reps you managed, and this free calculator estimates your 1RM using the Epley formula. You also get a full percentage table (95%, 90%, 80%…) so you know exactly what to load for each set. Works for bench press, squat, deadlift and any barbell lift, in kg or lb. Everything runs in your browser and nothing is uploaded.
Features
Estimate Your Max
Get your 1RM without a risky true-max attempt.
Percentage Table
Loads for 95%, 90%, 80%… so you know what to put on the bar.
kg or lb
Works in kilograms or pounds for any barbell lift.
100% Private
All calculations run in your browser; nothing is uploaded.
How to Use Your 1RM
Typical training zones
- Strength: 85–95% (2–5 reps)
- Hypertrophy: 67–80% (8–12 reps)
- Power: 50–70% (fast, low reps)
- Endurance: <67% (12+ reps)
Good to know
- Use a set taken close to failure
- Most accurate under ~10 reps
- 1RM is an estimate, not a guarantee
- Warm up before any heavy lift
Frequently Asked Questions
How is one rep max calculated?
This tool uses the Epley formula: 1RM = weight × (1 + reps ÷ 30). For a single rep, the 1RM equals the weight lifted. It's an estimate based on how many reps you did at a given weight.
How accurate is a 1RM estimate?
Estimates are most reliable when the set is taken close to failure and under about 10 reps. Above that, fatigue and technique make the number less precise.
Do I need to actually attempt a max?
No — that's the point. You lift a submaximal weight for several reps and the calculator estimates the max, which is safer and repeatable.
What are the training percentages for?
They tell you how much to load for a goal: e.g. strength work around 85–95% of 1RM, hypertrophy around 67–80%. The table shows the weight for each percentage.
Does it work for bench, squat and deadlift?
Yes. The formula applies to any barbell lift; calculate a separate 1RM for each exercise since your rep strength differs between them.