Feature

One Rep Max (1RM) Calculator

Plates calculates your estimated one rep max on every set, every session, automatically. Choose from three proven formulas, optionally adjust for RPE (Rate of Perceived Exertion), and track your strength trajectory over time without ever needing to test a true 1RM.

Exercise Progress screen showing a rising estimated 1RM chart, plus volume and best-set weight charts, for Bench Press over time

Three formulas, your choice

Different formulas suit different rep ranges and training styles. Plates lets you choose which one to use across the app:

Epley

1RM = weight x (1 + reps/30)

The most widely used formula in strength training. Slightly overestimates at very high reps but excellent across 1-15 rep range.

Best for: general training, higher rep ranges

Brzycki

1RM = weight x 36/(37 - reps)

Developed by Matt Brzycki. More conservative estimates, especially accurate in the 1-10 rep range. Popular with powerlifters.

Best for: powerlifting, low rep training

Hybrid

Brzycki under 8 reps, Epley over 10, blended 8-10

Uses the most accurate formula for each rep range with a smooth linear interpolation between 8-10 reps. Best of both worlds.

Best for: varied training, mixed rep ranges

RPE-adjusted calculations

A set of 5 reps at RPE 8 is not the same as 5 reps at RPE 10. Plates factors in your Rate of Perceived Exertion to produce more accurate estimates:

RPE 10 = 0 reps in reserve (true failure)
RPE 9 = 1 rep in reserve
RPE 8 = 2 reps in reserve
RPE 7 = 3 reps in reserve

The formula adds your Reps in Reserve (10 minus RPE) to the rep count before calculating. This means a set of 225 lbs x 5 at RPE 8 is treated as if you could have done 7 reps, giving a more realistic 1RM estimate.

Example: 225 lbs x 5 reps at RPE 8

Reps in Reserve 10 - 8 = 2

Effective reps 5 + 2 = 7

Epley estimate 225 x (1 + 7/30) = 278 lbs

Brzycki estimate 225 x 36/(37-7) = 270 lbs

Without RPE (5 reps only) Epley: 263 lbs / Brzycki: 253 lbs

Automatic tracking across every session

You never need to manually calculate. Plates computes your estimated 1RM on every logged set. These are all free:

Per-set e1RM - shown inline while you log (optional, toggle in settings)
Session best e1RM - highest estimate from that workout
e1RM trend chart - per exercise over time on the Exercise Progress screen, showing your strength trajectory

Records tab in the Progress hub (Pro)

Your personal records live in the Records tab of the Progress hub, which ranks every exercise by estimated 1RM. See your strongest lifts at a glance, with the weight, reps, and date for each personal best, and search or filter by exercise name or muscle group. A free preview card on the dashboard teases your most recent PRs; the full, searchable Records view is part of Plates Pro.

Why track estimated 1RM?

No max-out required - testing true 1RM is fatiguing, risky, and impractical to do frequently
Progress visibility - your e1RM can improve even when weight and reps stay the same (RPE drops)
Program prescriptions - percentage-based programs use your e1RM to calculate working weights
Trajectory forecasting (Pro) - with a live goal, Pro overlays a projected trend and estimated arrival date on the chart, so you can see whether you're on pace or stalling

Try Plates free

1RM tracking, formula selection, per-exercise trend charts, and the dashboard PR preview are free. The searchable Records hub and the goal trajectory forecast are part of Plates Pro: $2.99/month or $19.99/year, with a 14-day free trial.