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Rep max calculator — any N-rep max.
The rep max calculator converts between your one rep max and any target rep max — 3RM, 5RM, 8RM and more. Enter a set you hit or a known 1RM, and it uses the Epley relationship to build a full 1RM through 12RM table with the exact weight for each. It updates instantly, no signup.
Your full rep max table
The weight for every rep max from a single to a 12RM, with its approximate % of your one rep max.
| Rep max | Weight | % of 1RM |
|---|---|---|
| 1RM one rep max | — | — |
| 2RM 2 reps | — | — |
| 3RM 3 reps | — | — |
| 4RM 4 reps | — | — |
| 5RM 5 reps | — | — |
| 6RM 6 reps | — | — |
| 8RM 8 reps | — | — |
| 10RM 10 reps | — | — |
| 12RM 12 reps | — | — |
The formula, explained.
No black box. Every rep max is derived from your one rep max with the Epley relationship — here it is in full.
1RM = W × (1 + R ÷ 30) Epley — from a set of R reps at weight W. 100 kg × 5 → 117 kg.
nRM = 1RM ÷ (1 + n ÷ 30) The Epley inverse — the weight you can lift for n reps. 117 ÷ (1 + 5/30) ≈ 100 kg.
nRM ≈ 1RM × % A 5RM is about 86% of 1RM, a 3RM about 92%, a 10RM about 75%.
Most accurate for rep maxes of 1 to 10 reps. Above 10 reps, endurance skews the numbers, so treat higher rep maxes as a guide. Source: Epley one rep max relationship — the same equation used by ExRx.net and the NSCA. Brzycki is undefined at 37 reps, so this tool caps set input at 36.
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Same math, dialled in per lift and per goal — plus the tracker that puts your numbers to work.
Rep max questions.
What is a rep max?
A rep max is the heaviest weight you can lift for a given number of reps. A 5RM is the most you can lift for exactly 5 reps, a 3RM for 3 reps, and so on. Every rep max maps to a percentage of your one rep max, which is what this calculator converts between.
How do I calculate my 5RM from my 1RM?
To calculate a 5RM from a one rep max, divide the 1RM by 1 plus 5 over 30, using the Epley relationship. That works out to about 86 percent of your 1RM, so a 100 kg one rep max gives a 5RM near 86 kg. This calculator does the same math for every rep max from 1 to 12.
How many reps is 80% of my 1RM?
Roughly 80 percent of your one rep max is an 8-rep max for most lifters, using the Epley relationship. As a quick guide: 90 percent is about a 4RM, 85 percent about a 6RM, 80 percent about an 8RM, and 75 percent about a 10RM. Individual strength endurance shifts these by a rep or two.
How accurate is a rep max calculator?
A rep max calculator is most accurate within 1 to 10 reps, usually landing within about 5 to 10 percent of tested numbers. Above 10 reps, muscular endurance and conditioning matter more than pure strength, so treat higher rep maxes as a training guide rather than a precise target.
Is this rep max calculator free?
Yes, completely free with no signup. Save the result to your Nishaana account and it auto-applies your rep maxes to your next workout, so the weight for your target rep range is filled in for you at the rack.
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