1RM calculator
How much you could lift once, estimated from one hard set.
The 1RM calculator estimates your one rep max from the weight and reps of a hard set, using the Epley formula. Up to about 10 reps, the estimate is close to the real value [1].
Above 10 reps, the estimate gets less accurate.
Weight for 1 to 12 reps
Tap a row to see how to load the bar
How to load the bar
45 lb bar, plates per side
200 lbfor 5 reps
- 45
- 25
- 5
- 2.5
How does the calculator work?
It uses the Epley formula: max = weight × (1 + reps ÷ 30). So 185 lb × 8 gives about 234 lb (82.5 kg × 8 gives 104.5 kg). For 2 to 12 reps, it works backwards and rounds down to 5 lb (2.5 kg).
How accurate is it?
Up to about 10 reps, the estimate is close to your real max; in one comparison, Epley had the smallest average error and estimated slightly high [1]. Above that, the error grows, depending on the exercise and the person.
Use the number to compare with yourself, not as a target for a true max attempt.
What does Tarvo do with it?
Tarvo uses the same formula to spot your personal bests: if a set is stronger than any earlier one for the same exercise, you see it right away. Tarvo only shows the number from sets of 10 reps or fewer, and always as an estimate.
Questions
How do I calculate my 1RM?
Weight × (1 + reps ÷ 30). So 225 lb × 5 gives about 263 lb (100 kg × 5 gives about 117 kg).
Which 1RM formula is the most accurate?
In one comparison, Epley had the smallest average error, estimating slightly high [1]. More important than the formula: a set of 10 reps or fewer.
Does the calculator work for every exercise?
For weighted exercises, yes. On leg exercises, the estimate is less accurate: in one study, the error on the leg press was about five times that on the chest press [1].
Should I test my true max?
You don’t need to for training. A true attempt needs a warm-up, a spotter and a fresh day; the estimate is enough to see progress.
Sources
- [1]Reynolds, Gordon, Robergs (2006). Prediction of One Repetition Maximum Strength From Multiple Repetition Maximum Testing and Anthropometry. J Strength Cond Res 20(3). www.unm.eduStudy of 70 people. Formulas like Epley estimate the max well up to about 10 reps and less accurately beyond.
Keep going
Tarvo does the math after every set.
And spots a personal best the moment you check off the set.
One email when Tarvo launches. Nothing else. Privacy
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