One-Rep Max (1RM) Calculator
How it worksEstimate max strength from a submaximal set
Free one-rep max calculator using the Epley formula. Enter the weight you lifted and reps completed (1–15) to estimate your 1RM for programming percentages.
Estimated one-rep max
Enter the weight you lifted on the set — not your body weight.
Estimated 1RM
70.0 kg
≈ 154.3 lb
Working weights from this 1RM
About this 1RM calculator
A one-rep max (1RM) is the heaviest load you could lift once with solid technique. Testing true 1RMs is taxing and risky if form breaks down.
Submaximal estimators like the Epley formula let you predict 1RM from a set of several reps, then prescribe training as percentages of that estimate.
Estimates work best with controlled reps (not grinding failure with broken form) and tend to be less accurate as rep counts climb past ~10–12.
A one-rep max calculator estimates the heaviest single you could lift from a submaximal set, using the Epley formula. That lets you programme percentages without testing a risky true max every week.
Lifters searching “1RM calculator,” “bench press max,” or “Epley formula” want a fast, trustworthy estimate. We cap reps at 15 because higher reps drift from strength prediction quality.
Use estimates to plan Habbeat training days — then let progressive overload and recovery, not ego maxes, drive progress.
How to use this free tool
- Enter the weight on the bar (or machine stack) and how many clean reps you completed (1–15).
- We apply the Epley formula: weight × (1 + reps / 30).
- Use the estimate to set working sets (e.g. 70–85% for hypertrophy/strength blocks) — and re-test periodically as you progress.
Worked examples
- Example: 80 kg × 5 reps → Epley 1RM ≈ 80 × (1 + 5/30) ≈ 93 kg.
- Example: 100 kg × 3 reps → ≈ 100 × (1 + 3/30) ≈ 110 kg estimated max.
- Example: Programming a hypertrophy block at ~70–80% of estimated 1RM keeps loading intentional without weekly max tests.
Practical tips
- Warm up thoroughly before heavy sets; estimates assume the set was representative, not a messy grind.
- Use the same standard of depth/ROM every time you re-estimate.
- If you train with machines, keep estimates machine-specific — they don’t always transfer to free weights.
Limitations & caveats
- Form breakdown and high-rep grinders inflate error.
- Machine 1RMs don’t always transfer to free weights.
- True max testing needs experience, spotting, and recovery.
Frequently asked questions
What is the Epley formula?
Estimated 1RM = weight × (1 + reps / 30). Other formulas (Brzycki, Lombardi) exist; Epley is a popular default for mid-rep ranges.
Should I test a true 1RM?
Only if you are experienced, well spotted, and the program calls for it. Many lifters progress fine with estimated maxes and RPE.
Why limit reps to 15?
High-rep sets drift further from true max strength and inflate error. For endurance sets, track load × reps instead of chasing a 1RM.
What percentage of 1RM should I train at?
Hypertrophy often lives around ~65–80% for controlled sets; heavy strength work may use higher percentages for fewer reps. Programmes differ — match the plan you follow.
Epley vs Brzycki — which is better?
Both are estimators. Epley is a popular mid-rep default. If you switch formulas, stay consistent when comparing weeks.
Can beginners use a 1RM calculator?
Yes for rough loading, but focus first on technique. Stop sets before form collapses so the estimate stays meaningful.
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All toolsDisclaimer: These tools provide general estimates only. They are not medical advice. For health conditions, pregnancy, or personalised nutrition, speak with a qualified professional.