One Rep Max Calculator
Estimate your 1RM for any lift using your training weight and rep count. See your full strength curve, percentage targets, and how you compare against general and elite populations.
Estimation Formulas
Epley
Weight × (1 + Reps ÷ 30) — most widely used
Brzycki
More conservative, accurate at lower rep ranges
Mayhew (NFL)
Calibrated for high-rep sets, popularised by NFL combine
Average of All
Combines Epley, Brzycki, Lombardi & Mayhew
Your 1RM is the foundation of percentage-based programming. Knowing it lets you set precise training loads; whether you're peaking for strength, building hypertrophy, or testing progress.
The Basics
What is a 1RM?
Your Strength Baseline
The foundation of programming
Your one rep max is the maximum load you can lift for a single full-range repetition with good technique. It's the single most useful number in strength training because every training load, light, moderate, or heavy, is defined as a percentage of it.
Estimate, Don't Test
Safer and just as accurate
True 1RM testing is physically demanding and carries injury risk, especially for beginners. Mathematical formulas let you estimate it from a submaximal set, say, 100 kg for 10 reps, with accuracy within 2–5% of your actual max. Good enough to programme from.
Programme Precisely
Every lift, every rep zone
Once you know your 1RM, you can set exact loads for any goal. Strength work sits at 85–95% for low reps. Hypertrophy lands at 65–80% for moderate reps. Endurance and technique work uses 50–65%. The calculator gives you all of these targets automatically.
Choosing Your Formula
Formulas Explained
All 1RM formulas take the same two inputs, the weight you lifted and the number of reps you performed, and use a different mathematical model to extrapolate what you could do for a single maximum rep.
Epley is the default and the most commonly referenced formula in research. It tends to slightly overestimate at very high rep counts (15+) but is reliable for the 3–12 rep range most people train in.
Brzycki is more conservative and tends to be more accurate at low rep ranges (1–6 reps). If you're testing close to your actual max, Brzycki often gives the tightest estimate.
Lombardi and Mayhew were developed for higher-rep testing. Mayhew in particular was calibrated on NFL combine data, so it performs well for sets of 10 or more reps under fatigue conditions.
When in doubt, use Average of All. It smooths out the individual biases of each formula and typically lands within 1–2% of your actual 1RM across a wide range of rep counts.
Formula Comparison — 100 kg × 10 reps
Example based on 100 kg lifted for 10 reps.
Which Rep Range to Use
For the most accurate estimate, use your heaviest working set of the session, ideally 3–8 reps with 1–2 reps left in reserve. Sets to failure or beyond 12 reps reduce formula accuracy significantly.
Using Your 1RM
Percentage-Based Training
Strength Zone
85–95% of 1RM · 1–5 reps
Heavy loads close to your max develop maximal strength and neural drive. These sets are short, rest periods are long (3–5 min), and technique must be tight. Used in powerlifting peaking phases and strength-focused programmes like 5/3/1.
Hypertrophy Zone
65–80% of 1RM · 6–15 reps
The primary range for muscle growth. Moderate loads with sufficient volume create the mechanical tension and metabolic stress needed for hypertrophy. This is where most training volume should sit for body composition goals.
Endurance Zone
50–65% of 1RM · 15+ reps
Lighter loads for higher reps build muscular endurance, improve technique under fatigue, and support active recovery sessions. Useful for accessory work, beginners learning movement patterns, and deload weeks between heavy cycles.
Reading the Numbers
General vs Elite
Knowing your 1RM is only half the picture. Knowing where it sits relative to other people your age and gender gives you a realistic benchmark for your training stage, and a target to aim for.
The calculator compares your estimate against two populations: the general population (P10 to P90) and powerlifting elite. These ranges are expressed as percentiles, P50 means you're stronger than 50% of people in that category.
P10 to P25 is where most beginners land within their first year of training. P50 represents a solid intermediate. P75 and above is advanced territory, typically requiring 3–5 years of consistent structured training.
Elite powerlifting numbers represent the top fraction of competitive lifters, not a realistic target for most, but useful for context. They show the ceiling of human performance for your bodyweight and age bracket, adjusted by gender.
Use the percentile data to set realistic short-term goals. Moving from P25 to P50 on a Back Squat is a meaningful, achievable target over 6–12 months of consistent training.
Back Squat — Male 30–39 (approx. 80 kg BW)
Setting Realistic Targets
Beginners can expect to move up 1–2 percentile brackets per year. Focus on P50 first, reaching median for your demographic is a meaningful milestone that puts you well ahead of the average gym-goer. From there, each percentile step requires progressively more dedicated, structured training.