How to Calculate Your One Rep Max (2026)

Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It is the universal currency of strength training — used to set training loads, track progress, and compare performance across lifters. You do not need to actually attempt a true max lift to find your 1RM. Using a submaximal test and a validated formula, you can estimate it safely from a set of reps you can already perform. Use the One Rep Max Estimator to calculate yours instantly — no account needed, all processing stays in your browser.

The formulas behind 1RM estimation

Several equations exist for estimating 1RM from a submaximal effort. The most widely used is the Epley formula: 1RM = weight × (1 + reps / 30). If you lift 100 kg for 8 reps, your estimated 1RM is 100 × (1 + 8/30) = 100 × 1.267 = 127 kg. The Brzycki formula — 1RM = weight × 36 / (37 − reps) — produces similar results at moderate rep ranges (3–10 reps) and slightly different estimates at the extremes. Both formulas become less accurate above 12 reps, where fatigue and technique degrade the relationship between reps and absolute strength.

How to perform a submaximal test

Choose a weight you can lift for 3–10 reps to failure with good technique — this range gives the most reliable estimates. Warm up thoroughly, then perform the set at a controlled pace, stopping when you genuinely cannot complete another rep. Record the exact weight and rep count. Do not stop early; an incomplete set underestimates your 1RM. Rest at least 5 minutes before any follow-up attempts. One well-executed set is enough data for a solid estimate.

Using your 1RM to set training loads

Once you know your 1RM, you can back-calculate the right weight for any rep range. Strength and hypertrophy research uses percentage-of-1RM as the standard measure of training intensity. The table below shows the approximate relationship between 1RM percentage and achievable rep ranges for most compound lifts.

For example, if your squat 1RM is 140 kg and you want to run a hypertrophy block at 70%, load the bar to 98 kg and aim for sets of 10–12 reps. Reassess your 1RM every 4–8 weeks as you get stronger so your percentages stay calibrated. Use the One Rep Max Estimator to get your numbers and the corresponding training loads for any lift.