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One-Rep Max (1RM) Calculator

Estimate the heaviest weight you can lift for a single rep — without the injury risk of actually testing it. Then use the percentages to program your training.

kg
115kgestimated 1-rep max
100%115 kg
95%109 kg
90%104 kg
85%98 kg
80%92 kg
75%86 kg
70%81 kg
Get a full plan from these numbers →

Why estimate your 1RM?

Your one-rep max is the standard reference for programming strength training. Estimating it from a lighter set is far safer than grinding out a true max, and accurate enough to plan your working weights.

How it works

We average two trusted formulas (Epley and Brzycki) using a weight and the reps you completed with it. The closer your set is to 5 reps, the more accurate the estimate.

Using the percentages

Most strength programs prescribe work as a percentage of your 1RM — for example, 5×5 at 80%. The table gives you those exact weights so you can load the bar with confidence.

Frequently asked questions

How accurate is a 1RM calculator?

Very accurate for sets of 2–8 reps. The fewer reps you base it on, the more accurate it is. Above 10 reps, estimates drift, because endurance starts to matter more than pure strength.

Should I actually test my 1RM?

Rarely, and only when peaked and well-coached. For most lifters, estimating from a hard set of 3–5 reps is safer and just as useful for programming.

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