1RM calculator

How to use it

1. Enter the weight and reps of a recent hard set.
2. Pick the RPE you gave it. If you didn’t rate it, leave it on No RPE and the set counts as RPE 10.
3. Read your estimated 1RM (e1RM). The table below shows what it means for other rep counts.

How the estimate works

TopSet uses OpenPowerlifting’s RPE formula. It works out how many reps the set was from a true max single (x below), then turns that into a multiplier: the share of your 1RM the set used.

If you pick No RPE, the set counts as RPE 10, with no reps left. One rep at RPE 10 is your 1RM.

Example: 100 kg × 5 at RPE 8 gives x = 6, a multiplier of 0.8124 and an e1RM of 123.1 kg.

Heavy sets with low reps give the most reliable estimate. At 10 reps or more, it gets rough.

x = (10 − RPE) + (reps − 1)
x ≤ 2.92:  multiplier = (0.347619x² − 4.60714x + 99.9667) / 100
x > 2.92:  multiplier = (97.0955 − 2.64249x) / 100, never below 0.5
e1RM = weight ÷ multiplier