One-Rep Max Calculator
Enter the weight and reps from a set you’ve actually completed – we’ll estimate your true one-rep max and show you what to lift for any rep range.
Percentage of 1RM by Reps
| Reps | % of 1RM | Weight |
|---|
Percentage by Training Goal
| Goal | % of 1RM | Rep Range |
|---|---|---|
| Strength | 85-95% | 1-5 reps |
| Hypertrophy (Muscle Size) | 70-85% | 6-12 reps |
| Power / Speed | 50-70% | 3-5 reps (explosive) |
What Is a One-Rep Max (1RM)?
Your one-rep max is the heaviest weight you can lift for a single, full-range repetition with proper form. It's the standard reference point strength coaches use to design training programs, since most programs prescribe weight as a percentage of your 1RM rather than a fixed number.
Why Estimate Instead of Test?
Testing a true 1RM directly means working up to a near-maximal, all-out lift - useful for competitive lifters, but it carries a higher risk of injury for most people, especially without a spotter and a proper warm-up. Estimating your 1RM from a lighter, safer set (using the Epley and Brzycki formulas) gives you a reliable number without the risk, and it's accurate enough for programming your training.
How to Use This Calculator
Pick a set you've recently completed with good form - ideally somewhere in the 2-8 rep range, since estimates get less accurate above 10-12 reps. Enter the weight and reps, and the calculator averages the Epley and Brzycki formulas to give you a single estimate. Use the percentage table to plan your next training block: lower percentages for higher-rep hypertrophy work, higher percentages for low-rep strength work. If you're working through a structured block, our progressive overload guide and deload week guide cover how to build on these numbers over time without stalling.
Track Your Strength Alongside Your Physique
Your 1RM is one half of the picture - the other is body composition. Use Oneizar's free macro calculator to make sure your nutrition supports the strength you're building, and check your FFMI periodically to track your natural muscle potential over time.
Gear for Safer, More Accurate Testing
A spotter is always better, but this gear helps too
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