One rep max calculator

Your estimated 1RM from a set you've already done, plus the working weights for everything from doubles to twelves. No need to actually attempt a max.

Milo

Weight lifted (kg)

Reps completed

Your max will appear here.

How this is worked out

This uses the Epley formula, which turns any honest set into an estimated max:

1RM = weight × (1 + reps ÷ 30)

Rearranged, it gives the weight for any rep target, which is where the table comes from. It’s the same calculation Milo uses to carry weights forward between sessions, so a lift you log in chat and a number you get here won’t disagree.

Reps are capped at 12 for the estimate. Beyond that, a set is testing work capacity rather than strength, and every 1RM formula starts inflating badly — a set of 20 would predict a max most people can’t come close to lifting.

There’s no one-rep row in the table on purpose. Epley isn’t self-consistent at a single rep: run it forwards on one rep and it returns slightly more than the weight you lifted, so inverting it there would print about 97% of the max shown just above it. The estimate is the headline number instead.

The number is the easy part

Any calculator can hand you a figure. The hard bit is the next three months: eating roughly to it, noticing when it stops working, and changing it. Milo is a coach you text like a friend. You log what you ate in a sentence, and it learns your patterns, notices when your weight stalls, and adjusts the target from what you actually did rather than from a formula.

See how Milo works

Common questions

How accurate is an estimated 1RM?

Closest when the set was genuinely hard and in the 3 to 8 rep range. If you stopped with reps left in reserve, your real max is higher than this says. If your form degraded, it’s lower. Treat it as a working number for programming, not a record.

Should I test my actual one rep max?

Rarely, and only if you compete. A true max attempt is the highest-injury-risk thing in the gym and it takes days to recover from. Estimating from a set of five costs nothing and is accurate enough to program with.

Which percentages should I train at?

Broadly: 85%+ for strength in the 1 to 5 range, 70 to 85% for hypertrophy in the 6 to 12 range, below 70% for technique and volume. The table gives you those weights directly.

Why is my bench estimate less accurate than my squat?

Rep formulas fit lifts with a longer range of motion and more muscle mass better. Bench and overhead press tend to drop off faster rep to rep than squats and deadlifts, so an estimate from a high-rep bench set will usually read high.

Other calculators

Calories burned calculator — What a session actually costs, by activity, weight and time.
Heart rate zones — Your max heart rate and five training zones, from age or resting HR.
Running pace calculator — Pace, speed and what it projects over 5k, 10k and a marathon.
TDEE calculator — How many calories you burn in a day, and what to eat for your goal.
Calorie deficit calculator — How long a given deficit takes to reach your goal weight.

These are estimates from population averages, not measurements of you. Individual metabolism varies by roughly ±10% around any formula. Nothing here is medical advice — if you have a health condition, are pregnant, or are under 18, talk to a healthcare professional before changing how you eat or train.