1 Rep Max Calculator

Enter any weight × reps set and get your estimated 1RM across the three most common formulas — Epley, Brzycki, and Lombardi — plus a percentage table for programming your training.

Your set

Units

Weight lifted

Reps completed

Accuracy is best at 2-6 reps. Sets of 10+ reps over-estimate 1RM significantly because they're limited by muscular endurance, not maximal strength.

Estimated 1 rep max

260lb

Average of three formulas. Round to 260 lb for a realistic gym target.

By formula

Epley

Most common; trained on trained lifters

263 lb

Brzycki

Conservative above 5 reps

253 lb

Lombardi

Best for lower reps

264 lb

Log a set in Threshold, get a live 1RM estimate

Every working set updates your estimated max across every lift. Your coach progresses you when the numbers say you're strong, backs off when you're grinding.

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Programming percentages

% 1RM	Weight	Target reps	Purpose
100%	260 lb	1	Maximal strength · test day
95%	245 lb	2	Peak strength
90%	235 lb	3-4	Strength · low volume
85%	220 lb	4-6	Strength · working sets
80%	210 lb	6-8	Strength-hypertrophy blend
75%	195 lb	8-10	Hypertrophy · volume
70%	180 lb	10-12	Hypertrophy · higher volume
65%	170 lb	12-15	Endurance · technique
60%	155 lb	15+	Warmup · muscular endurance

Which formula should I use?

All three formulas agree within 2-3% at low reps (1-5). They diverge at high reps because they were each fit to different datasets. The consensus average above smooths out formula-specific bias.

Epley (1985) — the most widely cited formula. Tends to slightly over-estimate for very high rep sets, but is considered the default in most strength programs.
Brzycki (1993) — more conservative above 5 reps. Breaks down mathematically at 37+ reps (the denominator hits zero).
Lombardi (1989) — uses a power function. Best accuracy at low reps, less reliable above 10.

How to use the % table

Most strength programs prescribe work as a percentage of 1RM. The table above converts your estimated max into working weights for each training intensity:

Strength work (80-90%): low reps, long rest. Builds maximal force.
Hypertrophy (65-80%): moderate reps, moderate rest. Builds muscle.
Endurance / technique (60-70%): higher reps. Warmups, accessory work, movement quality.

A note on accuracy

Estimated 1RM is a guide, not a true max. Set-to-failure technique, bar speed, fatigue, and individual strength-endurance balance all affect the number. Use the estimate as a starting point and adjust based on how your working sets feel.

Your 1RM changes every week. This page doesn't.

Inside Threshold, every working set you log updates your estimated 1RM automatically. Your coach uses the current estimate to progress your lifts when you're strong and back off when you're grinding.

See Threshold