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Training Load from RPE Calculator

Find the load to lift for a target RPE and rep count.

How it is calculated

The tool treats RPE as reps in reserve and applies the Epley relationship backwards. RIR = 10 − RPE, reps to failure = reps + RIR, fraction of 1RM = 1 / (1 + reps to failure / 30), and working weight = 1RM × fraction. The one-rep max is in kilograms, reps is the target number of reps in the set, and RPE is a number from 1 to 10 (half points such as 7.5 work). The weight is shown to one decimal in kg and the percentage to two decimals. Anything outside those ranges, such as RPE 11 or 0 reps, returns no result. Epley is an estimate that drifts at high rep counts, so treat the output as a starting load.

Worked example

Take a 1RM of 140 kg, a set of 5 reps at RPE 8. RIR = 10 − 8 = 2, so you could do 5 + 2 = 7 reps to failure. Fraction = 1 / (1 + 7/30) = 0.8108, which is 81.08%. Working weight = 140 × 0.8108 = 113.5 kg. Result: load 113.5 kg, 81.08% of your 1RM.

Try this example →

Common mistakes

  • Entering your training weight or a rep-max set as the one-rep max. The field expects the single-rep maximum in kg, so use a tested or estimated 1RM.
  • Calling a set RPE 10 when it was really RPE 8 or 9. Inflated RPE gives a lighter load than you can handle, because RPE 10 means zero reps left.
  • Mixing up RPE and RIR. RPE 8 means 2 reps in reserve, not 8; the tool subtracts RPE from 10 itself.
  • Trusting the number for very high reps (around 15 or more). The Epley fit is loosest there, and fatigue and technique matter more than the formula.
  • Rounding the result straight to plates without checking how the set feels. The result is a starting prescription; adjust by RPE on the day.

Sources

About this calculator

RPE (Rate of Perceived Exertion) autoregulated training ties the weight on the bar to how hard a set actually feels rather than a fixed percentage of your one-rep max, using an RPE scale (popularized in powerlifting by Mike Tuchscherer) where RPE 10 means no reps left in the tank and RPE 8 means about two reps left. To turn a target reps-and-RPE combination into an actual working weight, the calculation takes your one-rep max and uses the Epley formula (1RM = weight × (1 + reps/30)) in reverse, with your reps plus the reps left in reserve at that RPE, to find the matching percentage of 1RM.

Powerlifters and strength coaches use RPE-based load prescriptions because they adjust automatically for daily readiness — a lifter having an off day naturally ends up with a lighter prescribed weight for the same RPE and rep target, without needing to reprogram the whole training block. It's a core tool in modern autoregulated periodization, used alongside or instead of straight percentage-based programming.

This calculator takes your one-rep max in kilograms, your target rep count and target RPE, and returns the working weight to load for that set and its percentage of 1RM. If you only know a recent lift, estimate your 1RM from it first with Epley's formula above.

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