1RM calculator

method notes

LiftGauge shows the formulas' low/high range and half-range ±% instead of pretending the mean is exact — with these equations the full range is about 5.6 % at 5 reps and 11.8 % at 12 reps (Epley, Brzycki, Lombardi, O'Conner, Wathan, Lander, Mayhew; RPE→%1RM source: Tuchscherer, Reactive Training Manual, RTS Press, 2008).

Velocity-based 1RM prediction is a parallel option — Muñoz-López et al. 2022 (PeerJ, PMID 35256919) showed the two-point load-velocity method estimates squat and deadlift 1RM with CV < 10 % when anchored at ~45 % and ~80 % of 1RM. For lift-locked variants with percentile readout against OpenPowerlifting raw meet records, see the bench press 1RM calculator, squat 1RM calculator, and deadlift 1RM calculator.

how to use it

1. Pick bar and units — pick your bar weight (15 kg, 20 kg, or 45 lb) and unit (kg or lb) using the chips at the top of the calculator.
2. Enter your top set — enter the load as the total weight on the bar (bar included; switch the "Load counts" chip to plates-only if you prefer the meet-card convention), the reps you completed at full range of motion, and the RPE you would call honestly. RPE 8–9 is the sweet spot for projection accuracy.
3. Read mean and spread — read the mean of all seven formulas (Epley, Brzycki, Lombardi, O'Conner, Mayhew, Lander, Wathan) plus a ± spread band. The mean is the honest read; any single formula overstates its precision.
4. Use the warmup ramp + RPE grid — read the suggested warmup ramp (percent-of-1RM × reps with plate-loading per side) and the RPE → load grid for off-day projections. The Prilepin readout flags the productive volume zone at your intensity.

frequently asked

How does a 1RM calculator work?

A 1RM calculator extrapolates from a sub-maximal set (load × reps at a given RPE) to the theoretical one-rep max. The math is a rep-to-1RM curve fitted on competition data: LeSuer et al. 1997 (J Strength Cond Res 11:211–213) tested seven of the most-used equations across squat, bench, and deadlift and found their group-mean accuracy within ±10 % at 5 reps for trained lifters.

Which 1RM formula is most accurate?

No single formula wins across all lifts and rep ranges. Epley reads roughly true on the squat and bench at 3–5 reps; Brzycki tends to read low past 6 reps; Mayhew and Lombardi spread more on bench than deadlift. LiftGauge shows the mean of all seven so the projection is anchored, with the spread reported as ± %.

What reps and RPE should I use as input?

RPE 8–9 at 3–6 reps is the sweet spot. The seven formulas read load × reps only; RPE drives the separate RPE-adjusted (Tuchscherer) estimate row, the warmup ramp, and the RPE → load grid. RPE 6–7 stretches the anchor table past its validated range, and beyond 8 reps all formulas degrade — they were validated in the 1–6 rep range.

Why show seven 1RM formulas instead of one?

Because they disagree, and which fits best depends on the lift, lifter, and rep range. With the implemented equations the full low-to-high range is about 5.6 % at 5 reps and 11.8 % at 12 reps. Showing all seven surfaces estimator disagreement instead of hiding it behind one false-precision number.

Touch-and-go or paused reps for input?

For meet-relevant 1RMs, use paused reps (bench), full-depth (squat), and dead-stop (deadlift). Touch-and-go bench inflates the projection by 3–6 %, high squats by 5–10 %, and touch-and-go deadlifts by 3–8 %. For training 1RMs either works but stay consistent across cycles for tracking.

How often should I test my 1RM?

For peaking blocks, every 6–8 weeks at most; for off-season strength work, every 12–16 weeks. Daily projection from training sets (this page) replaces frequent maxing — that is the entire point of an RPE-anchored 1RM estimate.