One Rep Max Calculator
Enter a weight and the reps you managed to estimate your one rep max, compare three formulas and get training weights from 60% to 95%.
- Epley, Brzycki, Lombardi
- % of 1RM chart
- lb or kg
- No max-out needed
One rep max (1RM)
Fill in the boxes. The answer appears as you type.
What is a one rep max?
Your one rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is tiring and risky, so lifters estimate it from a lighter set taken close to failure. This calculator uses three well-known formulas: Epley (weight × (1 + reps ÷ 30)), Brzycki (weight × 36 ÷ (37 − reps)) and Lombardi (weight × reps^0.10), and shows the training weight for common percentages of your max, with the reps typically possible at each.
How to use One Rep Max Calculator
- Do a set of 3–10 reps close to failure with good form.
- Enter the weight, the reps and your unit.
- Read your estimated 1RM and compare the three formulas.
- Use the percentage chart to pick weights for your programme.
1RM formulas
- Epley: 1RM = w × (1 + r/30). Popular and slightly generous at higher reps.
- Brzycki: 1RM = w × 36 / (37 − r). Accurate for under 10 reps.
- Lombardi: 1RM = w × r^0.10. More conservative at high reps.
- Estimates are most accurate between 3 and 10 reps; above about 12 they become unreliable.
Why use this one rep max calculator
- Answers as you typeNo Calculate button. Change any number and every result updates instantly.
- Clear, sourced rules of thumbEach formula is named and explained, so you know where the number comes from and its limits.
- Training chart included95% down to 60% of your max with typical rep ranges.
- PrivateYour numbers are calculated on your device and never sent anywhere.
Common uses
- Programming. Set weights for 5/3/1, Starting Strength or percentage-based plans.
- Tracking progress. Compare estimated maxes over time without maxing out.
- Bench, squat and deadlift. Works for any lift.
- Coaches. Estimate athletes’ maxes from training sets.
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Example: 185 lb for 5 reps
Epley: 185 × (1 + 5/30) = 215.8 lb. Brzycki: 185 × 36 / 32 = 208.1 lb. Lombardi: 185 × 5^0.10 = 217.3 lb.
What to expect from the result
Estimates assume the set was close to failure with consistent technique. Individual results vary with training experience and muscle fibre type. Always use a spotter or safety bars for heavy lifts.
One Rep Max Calculator questions
How do I calculate my one rep max?
Lift a weight for as many good reps as you can (ideally 3–10), then enter the weight and reps. The Epley formula multiplies the weight by 1 + reps ÷ 30.
Which 1RM formula is most accurate?
For low reps, Epley and Brzycki agree closely. Brzycki tends to be more accurate below 10 reps; Lombardi is more conservative at higher reps.
Is it safe to test a true 1RM?
It can be with good technique, a warm-up and a spotter, but estimating from a submaximal set is safer and less fatiguing.
What percentage of my max should I train at?
Strength work is often 80–90% for 3–6 reps; hypertrophy 65–80% for 8–12 reps. See the chart under your result.
Does it work in kilograms?
Yes. Choose kg; the formulas work the same in any unit.