1 Rep Max Calculator
Estimate your one-rep maximum (1RM) instantly using six validated formulas — Epley, Brzycki, Lander, Lombardi, Mayhew, and O'Conner. Enter the weight you lifted and the reps you completed to get your estimated 1RM, a formula comparison table, and a full percentage-based training load table from 60% to 100% of your 1RM. No signup required — all calculations run locally in your browser.
Enter the weight you lifted and the number of reps completed to estimate your one-rep maximum (1RM) using six validated formulas. See a full percentage-based training table for programming your workouts. All calculations run locally in your browser — no signup required.
The weight you used for the set
Reps performed (1–30)
- Epley: 1RM = weight × (1 + reps / 30)
- Brzycki: 1RM = weight × 36 / (37 − reps)
- Lander: 1RM = (100 × weight) / (101.3 − 2.67 × reps)
- Results are estimates — actual 1RM may vary with fatigue, technique, and exercise selection
Why Use Our 1 Rep Max Calculator?
Instant 1 Rep Max Calculation
Calculate your estimated one-rep max instantly in your browser with zero wait time. Our 1 rep max calculator runs six validated formulas simultaneously — Epley, Brzycki, Lander, Lombardi, Mayhew, and O'Conner — and shows the average in milliseconds.
Secure 1 Rep Max Calculator Online
All 1 rep max calculations happen locally in your browser — your training data never leaves your device. Use our 1 rep max calculator online with complete privacy and zero data collection, every single time.
1 Rep Max Calculator — No Installation
Use our 1 rep max calculator directly in any browser with no downloads, plugins, or app installs required. Calculate your 1RM from any device, anywhere — desktop, tablet, or mobile — instantly.
Six Formulas + Full Training Load Table
Our 1 rep max calculator compares six peer-reviewed formulas side by side and generates a complete percentage-based training table from 60% to 100% of your 1RM — with target reps and training zones for strength, hypertrophy, and endurance programming.
Common Use Cases for 1 Rep Max Calculator
Strength Training Program Design
Coaches and athletes use the 1 rep max calculator to set training loads for powerlifting, Olympic weightlifting, and strength programs. Knowing your 1RM lets you prescribe precise percentages for each training block — 85% for strength, 75% for hypertrophy, 65% for endurance.
Safe 1RM Testing Without Maxing Out
Attempting a true 1RM carries injury risk, especially for beginners. Use our 1 rep max calculator to estimate your max from a submaximal set — lift 80% for 8 reps and get an accurate 1RM estimate without the risk of a true max attempt.
Progress Tracking Over Time
Track strength gains by calculating your estimated 1RM at regular intervals. Comparing 1RM estimates over weeks and months gives a clear picture of strength progression even when you never attempt a true maximum lift.
Competition Attempt Selection
Powerlifters and weightlifters use the 1 rep max calculator to plan opening, second, and third attempts for competition. Knowing your estimated 1RM helps you select conservative openers and aggressive third attempts to maximise your total.
Gym Class & Group Fitness Programming
Personal trainers and CrossFit coaches use the 1 rep max calculator to set scaled weights for group classes. Prescribing loads as a percentage of 1RM ensures every athlete works at the appropriate intensity regardless of their strength level.
Rehabilitation & Return to Sport
Physical therapists use the 1 rep max calculator to set safe loading parameters during rehabilitation. Estimating 1RM from light submaximal sets allows progressive overload without exposing recovering athletes to heavy loads prematurely.
Understanding the 1 Rep Max Calculator
What is a 1 Rep Max (1RM)?
A 1 Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form for a given exercise. It is the gold standard measure of absolute strength in powerlifting, Olympic weightlifting, and strength training. Our 1 rep max calculator estimates your 1RM from a submaximal set — the weight you lifted and the number of reps you completed — using six validated mathematical formulas. The average of all six formulas gives the most reliable estimate, while the individual formula results show the range of possible values.
How Our 1 Rep Max Calculator Works
- 1. Enter Your Lift Data: Input the weight you lifted, the number of reps you completed, and your preferred unit (kg or lbs). For best accuracy, use a set of 2–6 reps at near-maximal effort. All processing happens locally in your browser — your training data never leaves your device.
- 2. Six Formulas Calculated Instantly: Click Calculate 1RM to run all six formulas simultaneously — Epley, Brzycki, Lander, Lombardi, Mayhew, and O'Conner. The calculator shows each formula's result, highlights the highest and lowest estimates, and displays the average.
- 3. Use Your Training Load Table: The percentage table shows the weight to use at 60–100% of your estimated 1RM, with target rep ranges and training zones — ready to plug directly into your program.
The Six 1RM Formulas Explained
- Epley (1985): 1RM = weight × (1 + reps / 30). The most widely used formula in strength and conditioning. Slightly overestimates at higher rep counts but is reliable for 2–10 reps.
- Brzycki (1993): 1RM = weight × 36 / (37 − reps). Considered the most accurate for sets of 2–10 reps. Becomes unreliable above 10 reps as the denominator approaches zero.
- Lander (1985): 1RM = (100 × weight) / (101.3 − 2.67 × reps). A conservative linear model that tends to produce slightly lower estimates than Epley.
- Lombardi (1989): 1RM = weight × reps^0.1. A power-based formula that produces moderate estimates across a wide rep range.
How to Use Your 1RM for Training
The percentage-based training table generated by our 1 rep max calculator maps directly to standard strength programming zones. 90–100% of 1RM (1–3 reps) develops maximal strength. 75–85% of 1RM (5–10 reps) is the primary hypertrophy and strength-hypertrophy range used in most intermediate programs. 65–75% of 1RM (10–15 reps) targets hypertrophy and muscular endurance. Below 65% (15+ reps) develops muscular endurance and is used for warm-ups, deload weeks, and technique work. Always use your estimated 1RM as a guide — actual training loads should be adjusted based on daily readiness, fatigue, and technique quality.
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Frequently Asked Questions About 1 Rep Max Calculator
A 1 rep max calculator estimates the maximum weight you can lift for a single repetition from a submaximal set. Our 1 rep max calculator uses six validated formulas — Epley, Brzycki, Lander, Lombardi, Mayhew, and O'Conner — and shows the average as the recommended estimate. All calculations run locally in your browser.
The Brzycki formula is generally considered the most accurate for sets of 2–10 reps. The Epley formula is the most widely used in strength and conditioning. For the most reliable estimate, our 1 rep max calculator averages all six formulas — this reduces the impact of any single formula's bias and gives a more robust result.
All 1RM formulas are most accurate for sets of 2–6 reps at near-maximal effort. Sets of 1–3 reps give the most accurate estimates. Accuracy decreases as rep count increases — above 10 reps, estimates can be off by 10–15%. For best results, use a weight you can lift for 3–5 reps with maximum effort.
True 1RM attempts carry injury risk, especially for beginners and intermediate lifters. Our 1 rep max calculator lets you estimate your 1RM from a submaximal set without the risk of a true max attempt. If you do attempt a true 1RM, always use a spotter, warm up thoroughly, and approach the weight gradually with multiple build-up sets.
Yes — the 1RM formulas work for any barbell or dumbbell exercise: squat, bench press, deadlift, overhead press, row, and more. However, 1RM formulas are most reliable for compound barbell movements. For isolation exercises or machine exercises, the estimates may be less accurate due to different fatigue patterns.
The training load table shows the weight to use at 60–100% of your estimated 1RM, with target rep ranges and training zones. Use 85–95% for strength work (3–5 reps), 75–85% for strength-hypertrophy (5–8 reps), 65–75% for hypertrophy (10–12 reps), and 60–65% for muscular endurance (15–20 reps).
Yes! Our 1 rep max calculator is 100% free with no signup, no ads, and no usage limits. Calculate your 1RM as many times as you need — completely free, forever.
Absolutely. All 1 rep max calculations happen locally in your browser using JavaScript. Your weight, reps, and training data are never sent to any server, ensuring complete privacy every time you use our 1 rep max calculator online.
Each formula uses a different mathematical model to describe the relationship between weight, reps, and maximal strength. They were derived from different populations and exercise types, so they produce slightly different results. The range between the highest and lowest formula is typically 3–8% — our 1 rep max calculator shows all six results so you can see the full range and use the average for programming.