What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Coaches use it as a reference point: most programmes prescribe work as a percentage of 1RM — for example “4 sets of 6 at 80%”.
Testing a true max is tiring and carries more injury risk, especially for beginners. Estimating it from a set of 3–10 reps is safer and accurate enough for planning training.
1RM percentage chart
| % of 1RM | Reps you can usually do | Training goal |
|---|---|---|
| 90–100% | 1–4 | Maximal strength, peaking |
| 80–89% | 4–8 | Strength |
| 67–79% | 8–12 | Muscle growth (hypertrophy) |
| Below 67% | 12+ | Muscular endurance, technique, warm-ups |
Muscle grows across a wide range of loads as long as sets are taken close to failure, so you don't have to train heavy to build size. Heavier work mainly improves your ability to lift heavy.
How to use your 1RM in training
- Pick a rep target from the table in your results and use that load for your working sets.
- Leave 1–3 reps in reserve on most sets. The table loads are close to all-out efforts, so start slightly lighter.
- Progress gradually: once you can beat your rep target at a load, add 2.5 kg (upper body) or 5 kg (lower body). See progressive overload.
- Re-estimate every 4–6 weeks from a recent hard set, so your percentages keep up with your strength.
How accurate are 1RM formulas?
With sets of about 10 reps or fewer, estimates are usually within 5–10% of a tested max. Accuracy drops with higher reps, with fatigue, and for lifters whose endurance is unusually good or poor for their strength. Different lifts also behave differently — many people can do more reps at a given percentage on squats and leg press than on bench press. That's why we cap the input at 12 reps and show two formulas side by side.
Is my 1RM good?
Compare yourself with your past self first. As a rough guide for adult men after 1–2 years of consistent training, a bench press around body weight, a squat around 1.25–1.5× and a deadlift around 1.5–2× body weight are solid intermediate numbers. Women often reach about 0.6×, 1× and 1.25× body weight respectively.
Strength gains depend on eating enough protein — use the protein calculator to check your target.
Worked example: Rohan's bench press
Rohan benches 80 kg for 5 reps.
Epley: 80 × (1 + 5 ÷ 30) = 93.3 kg. Brzycki: 80 × 36 ÷ (37 − 5) = 90.0 kg. Average: about 91.7 kg.
For sets of 8 he would use about 80% — 72.5 kg — and for sets of 10–12, about 65–70 kg. He doesn't need to test a single to train effectively.
How this calculator works
We average two widely used prediction equations: Epley, 1RM = weight × (1 + reps ÷ 30), and Brzycki, 1RM = weight × 36 ÷ (37 − reps). For a single rep, your 1RM is the weight entered. Inputs are limited to 1–12 reps because prediction error grows quickly beyond that.
The load table uses common reference percentages for each rep count and rounds to the nearest 2.5 kg or lb, the smallest jump most gyms allow.
Frequently asked questions
Straight answers about this calculator. Educational only — not medical advice.
Do a hard set of 3–10 reps with good form, then enter the weight and reps here. The Epley formula is weight × (1 + reps ÷ 30); we average it with the Brzycki formula.
Usually not. In the first few months strength rises quickly and technique is still developing. Estimating from a 5–8 rep set is safer and just as useful.
No single formula wins for everyone. Epley tends to read a little higher and Brzycki a little lower at moderate reps, so averaging them is a sensible middle ground.
Yes, for any barbell or machine lift you can do with steady form. Estimates are most reliable for compound lifts in the 3–10 rep range.
Every 4–6 weeks, using a hard set from your normal training, is enough to keep training percentages accurate.
Related calculators
Guides to read next
Get weekly tips that build on your numbers
Simple meal ideas, protein swaps and training cues — on Instagram and Facebook.
This calculator provides an estimate and isn't a substitute for individualised medical or dietary advice. Read our medical disclaimer and editorial policy.