One-Rep Max Calculator
Estimate your one-rep max (1RM) from a hard set using the Epley and Brzycki equations — plus a load table for programming your training percentages.
Epley 116.7 kg · Brzycki 112.5 kg
Training loads from your 1RM
| % of 1RM | Load (kg) | ≈ Reps |
|---|---|---|
| 100% | 115 | 1 |
| 95% | 110 | 2 |
| 90% | 102.5 | 4 |
| 85% | 97.5 | 6 |
| 80% | 92.5 | 8 |
| 75% | 85 | 10 |
| 70% | 80 | 12 |
Educational estimate, not coaching or medical advice. Prediction equations are most accurate for sets of ~6 reps or fewer and approximate beyond ~10–12. Loads are rounded to the nearest 2.5 kg / 5 lb; autoregulate with RPE/RIR rather than chasing an exact number, and warm up thoroughly before heavy work.
Train with your recovery, not against it
ONDA Life connects your strength work to sleep, HRV and readiness — so you push when your body can handle it and back off when it can’t.
Download ONDA Life on the App Store →Sources & methodology
Your one-rep max is estimated from a sub-maximal set using two established equations: Epley (1985), 1RM = weight × (1 + reps/30), and Brzycki (1993), 1RM = weight × 36 / (37 − reps). They track each other closely at low reps and diverge as reps rise, so we report both and their average. A validation study (LeSuer 1997) found such equations most accurate at roughly 6 reps or fewer and increasingly approximate beyond ~10–12 reps — so a heavy triple predicts your max far better than a light set of 15. Loads in the table are the average estimate scaled to common %1RM training targets, rounded to the nearest 2.5 kg / 5 lb. This is an estimate, not a substitute for a properly warmed-up, supervised max test.
- [1] Brzycki M (1993). Strength testing — predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance, 64(1):88–90.
The Brzycki prediction equation (1RM = w · 36 / (37 − reps)) used here.
- [2] LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD (1997). The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research, 11(4):211–213.
Validation showing these equations are most accurate at low reps and lose accuracy past ~10 reps.
Common questions
Where do these 1RM numbers come from?
The estimate uses the Epley (1985) and Brzycki (1993) prediction equations and reports their average; a validation study (LeSuer 1997) found such formulas most accurate at low reps. Full citations are in the Sources section on this page. For best accuracy, enter a set of 6 reps or fewer.
How accurate is an estimated one-rep max?
Very good when the set is heavy and short. Prediction equations correlate strongly with measured 1RM (r > 0.95) for sets up to about 6 reps, then drift as reps increase because endurance and technique start to dominate. Treat a number from a set of 12+ as a ballpark only.
How many reps should I enter for the best estimate?
Use a recent, genuinely hard set of 2–6 reps where the last rep was close to failure with good form. That range sits in the sweet spot of the prediction equations. Avoid using sets taken well short of failure — they will under-estimate your max.
Should I actually train at these percentages?
The load table is a starting point for programming: heavy strength work sits around 85–95% for low reps, hypertrophy around 67–80% for moderate reps, and technique or speed work lower. Real readiness varies day to day, so use RPE/RIR (reps in reserve) to autoregulate rather than chasing the exact number.
Is it safe to test my true one-rep max?
For trained lifters with sound technique it can be, but it carries more injury risk and fatigue than a sub-maximal estimate — which is why most coaches program from estimated maxes. If you do test, warm up thoroughly, use a spotter or safeties, and stop if form breaks down. This tool is educational, not coaching or medical advice.