Handy tools
1RM Calculator
Estimate your one-rep max from a lighter set, with a %1RM chart and strength grade.
Estimate your one-rep max (1RM) from a lighter set: enter the weight in kg or lb and the reps you completed. You get the average of the Epley and Brzycki formulas, a %1RM training chart and a strength level relative to your bodyweight.
Epley 262.5 lb · Brzycki 253.1 lb. The big number is their average.
- Epley formula
- 262.5 lb
- Brzycki formula
- 253.1 lb
- Average
- 257.8 lb
%1RM training chart
| % of 1RM | Weight | Approx. reps |
|---|---|---|
| 100% | 257.8 lb | ~1 reps |
| 95% | 244.9 lb | ~2 reps |
| 90% | 232 lb | ~4 reps |
| 85% | 219.1 lb | ~6 reps |
| 80% | 206.2 lb | ~8 reps |
| 75% | 193.4 lb | ~10 reps |
| 70% | 180.5 lb | ~12 reps |
| 65% | 167.6 lb | ~15 reps |
| 60% | 154.7 lb | ~18 reps |
Rep counts come from the same two formulas worked backwards and averaged. Real numbers vary by person, lift and fatigue.
Strength level
Your estimated 1RM is 1.56× your bodyweight: Intermediate level.
Thresholds are rough bodyweight multiples by lift and sex, not official standards or a health assessment.
⚠️ This is an estimate, so you don't need to max out to use it. If you do test a true 1RM, build up through gradually heavier warm-up sets and use a spotter or safety bars. If you're new to lifting, injured or have a health condition, skip max attempts.
Average of the Epley and Brzycki formulas. Most reliable for sets of 10 reps or fewer; error grows beyond that. Enter 1 rep and the weight you lifted is your 1RM. For reference only, not medical or coaching advice.
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Giggleus's 1RM calculator estimates your one-rep max from a lighter set. Enter the weight in kg or lb and the reps you completed (1 to 20) for squat, bench press, deadlift or overhead press, and it averages two standard formulas: Epley, weight × (1 + reps ÷ 30), and Brzycki, weight × 36 ÷ (37 − reps). For example, 100 kg for 5 reps gives 116.7 kg (Epley) and 112.5 kg (Brzycki), so an estimated 1RM of about 114.6 kg.
You also get a %1RM chart from 60% to 100% with the approximate reps for each load, and a rough strength level from beginner to elite based on your 1RM as a multiple of bodyweight. Estimates are most reliable for sets of 10 reps or fewer. You don't need to test a true max to use it; if you do, warm up gradually and use a spotter or safety bars.
Frequently Asked Questions
Q. How do you calculate a one-rep max?
A. This calculator averages two formulas: Epley, weight × (1 + reps ÷ 30), and Brzycki, weight × 36 ÷ (37 − reps). For 100 kg × 5 reps that gives about 114.6 kg.
Q. How accurate is an estimated 1RM?
A. It is most reliable for sets of 10 reps or fewer; above that the two formulas drift apart and error grows. A single rep entered as 1 is treated as your actual 1RM.
Q. What weight should I use for a given number of reps?
A. The %1RM chart lists loads from 60% to 100% of your estimate with approximate reps, for example about 8 reps at 80% and about 5 to 6 at 85%. Individual results vary.
Q. Is it safe to test my real 1RM?
A. It carries injury risk, which is why estimating from a lighter set is popular. If you test it, warm up with gradually heavier sets and use a spotter or safety bars; beginners and anyone injured should skip max attempts.