One Rep Max Calculator
| % of 1RM | Weight |
|---|
- Epley: 1RM = w × (1 + reps/30)
- Brzycki: 1RM = w × 36 / (37 − reps)
- Lombardi: 1RM = w × reps0.10
- Mayhew: 1RM = 100w / (52.2 + 41.9 × e−0.055×reps)
Your one rep max (1RM) is the heaviest weight you can lift for a single clean rep, and this calculator estimates it without you having to attempt a risky max lift. Enter a weight and how many reps you hit with it, and it averages four proven formulas (Epley, Brzycki, Lombardi, and Mayhew) for a reliable number. Lift 225 lb for 5 reps, for example, and your estimated 1RM is about 262 lb. It also builds your training percentages so you know exactly what to load for strength, muscle, or endurance work.
Below you will find the 1RM percentage chart, how to convert any rep max to your 1RM, worked examples for bench, squat, and deadlift, and how the four formulas differ.
What Is a One Rep Max (1RM)?
Your one rep max is the most weight you can lift for one complete repetition with correct form. It is the standard way lifters measure raw strength, and it is the number most training programs are built around.
Testing your true 1RM by actually loading a max lift is risky, especially without a spotter. That is why most lifters estimate it instead. You take a weight you can lift for a few reps, plug in the numbers, and a formula predicts what you could handle for a single rep. It is safer, nearly as accurate, and you can do it on any working set.
Knowing your 1RM matters because almost every program prescribes weight as a percentage of it. “Work up to 80 percent” means nothing until you know your max. Once you do, you can set the right load for strength, muscle growth, or endurance, and track progress objectively over months.
How to Calculate Your One Rep Max
The most common way to estimate 1RM is the Epley formula, which is simple enough to do in your head:
1RM = Weight × (1 + Reps ÷ 30)
Say you lifted 80 kg for 6 reps:
1RM = 80 × (1 + 6 ÷ 30)
1RM = 80 × 1.20
1RM = 96 kg
That is your estimated one rep max. The calculator above does this automatically, but it does not stop at one formula. It runs four different equations and averages them, because no single formula is perfect for every rep range or lifter. More on those formulas further down.
Which Rep Range Is Most Accurate?
These formulas are most reliable when you use a weight you can lift for 3 to 8 reps with solid form. Below 3 reps there is little to estimate; above 10 to 12 reps the prediction drifts because fatigue and technique start to matter more than raw strength. For the best result, pick a set you finished cleanly without hitting failure.
1RM Percentage Chart (Reps to Max)
This chart shows roughly what percentage of your 1RM you can lift for a given number of reps. Read it two ways: to estimate your max from a rep set, or to pick a weight for a target rep count.
| Reps | % of 1RM |
|---|---|
| 1 rep | 100% |
| 2 reps | 94% |
| 3 reps | 91% |
| 4 reps | 88% |
| 5 reps | 86% |
| 6 reps | 83% |
| 7 reps | 81% |
| 8 reps | 79% |
| 9 reps | 77% |
| 10 reps | 75% |
| 12 reps | 71% |
| 15 reps | 67% |
So if you can bench 10 reps at a given weight, that weight is about 75 percent of your max. Flip it around and multiply that weight by 1.33 to estimate your 1RM.
How to Convert a Rep Max to Your 1RM
People often know their 5 rep max or 10 rep max and want the single. Here are the quick Epley multipliers. Take the weight you lifted for that many reps and multiply:
| Rep Max | Multiply By | Example (100 lb) |
|---|---|---|
| 3 rep max (3RM) | 1.10 | 110 lb 1RM |
| 5 rep max (5RM) | 1.17 | 117 lb 1RM |
| 8 rep max (8RM) | 1.27 | 127 lb 1RM |
| 10 rep max (10RM) | 1.33 | 133 lb 1RM |
For example, if your 10 rep max squat is 225 lb, your estimated 1RM is 225 × 1.33 = about 300 lb. This is exactly what the calculator does when you enter reps above 1, just with four formulas averaged instead of one.
Training Load Percentages (What to Lift for Your Goal)
Once you know your 1RM, you can set the right weight for what you are training. These are the standard zones:
| Goal | % of 1RM | Reps |
|---|---|---|
| Max strength / power | 85 to 100% | 1 to 5 |
| Strength | 80 to 90% | 4 to 6 |
| Muscle growth (hypertrophy) | 65 to 80% | 6 to 12 |
| Endurance | 40 to 65% | 12 to 20 |
| Technique / warm-up | 30 to 50% | Light, easy |
The calculator builds this full percentage table from your estimated max automatically, so you can read your working weights straight off your result.
1RM Examples for Bench, Squat, and Deadlift
Here are worked examples using the four-formula average, so you can sanity-check your own numbers.
Bench Press 1RM Example
You bench 225 lb for 5 reps. Estimated 1RM is about 262 lb. The more reps you complete at a given weight, the higher your estimated single, so hitting 225 for 8 reps would point to a stronger max than 225 for 3 reps.
Squat 1RM Example
You squat 100 kg for 5 reps. Estimated 1RM is about 116 kg. If you can hit 100 kg for 10 reps instead, your estimated max jumps to around 133 kg, because grinding out more reps at the same weight signals a much stronger single.
Deadlift 1RM Example
You deadlift 140 kg for 3 reps. Estimated 1RM is about 154 kg. Deadlifts are often tested at low reps because heavy pulls fatigue you fast, so a 3 to 5 rep set is a reliable input here.
Popular “If I Lift X for Y Reps” Answers
- If you squat 225 for 10 reps: estimated max about 295 lb
- 155 for 5 reps: estimated max about 180 lb
- 175 for 6 reps: estimated max about 209 lb
- 315 for 6 reps: estimated max about 376 lb
Enter your own weight and reps in the calculator for an instant estimate on any lift.
The Four 1RM Formulas Explained
This calculator averages four science-backed formulas. Each one behaves a little differently, which is why using several gives a steadier estimate than trusting just one.
Epley
The most widely used formula, good for compound lifts across most rep ranges.
1RM = w × (1 + reps ÷ 30)
Brzycki
Accurate in the 2 to 10 rep range and slightly more conservative than Epley at moderate reps.
1RM = w × 36 ÷ (37 − reps)
Lombardi
Uses an exponent rather than a linear factor, often preferred for experienced lifters.
1RM = w × reps^0.10
Mayhew
Built from research on bench press performance, it holds up well at higher rep counts.
1RM = 100w ÷ (52.2 + 41.9 × e^(−0.055 × reps))
At 80 kg for 6 reps, these give 96.0, 92.9, 95.7, and 97.2 kg respectively, averaging about 95 kg. The small spread between them is normal and is exactly why an average is more trustworthy than any single number.
How Accurate Is a One Rep Max Calculator?
For most lifters, these estimates land within about 5 to 10 percent of a true tested max. Accuracy is highest when you use strict form, pick a weight in the 3 to 8 rep range, and stop short of failure. It drops off if you guess your reps, let form break down, or use very high rep sets.
Treat the number as a well-informed estimate, not an exact figure. Its real value is tracking change over time. If your estimated max climbs month over month, you are getting stronger, and that trend is more useful than any single reading.
How Much Should I Be Able to Lift?
There is no single answer, since strength depends on body weight, training age, sex, and the lift itself. A rough rule many coaches use for an intermediate male lifter is a bench around body weight, a squat around 1.5 times body weight, and a deadlift around 2 times body weight, though plenty of people are above or below this. Rather than comparing to others, use your 1RM to compete with your past self. Add a little weight or a rep over time and your max will follow.
Frequently Asked Questions
How do you calculate one rep max?
Use the formula 1RM = weight × (1 + reps ÷ 30). Enter a weight you lifted and the reps you completed, and it estimates your single-rep max. The calculator above averages four formulas for a more reliable result.
How do I convert my 5 rep max to 1 rep max?
Multiply your 5 rep max weight by about 1.17. For example, a 200 lb 5RM gives an estimated 1RM near 234 lb. For a 10 rep max, multiply by roughly 1.33 instead.
Are one rep max calculators accurate?
They are usually within 5 to 10 percent of a true max when you use good form and a 3 to 8 rep set. They are less accurate with very high reps or guessed numbers. For tracking progress, they are reliable and much safer than testing a true max.
What percentage of my 1RM should I lift?
It depends on your goal. Strength work sits around 80 to 90 percent for low reps, muscle growth around 65 to 80 percent for moderate reps, and endurance around 40 to 65 percent for higher reps.
What does 1RM mean?
1RM stands for one rep max, the most weight you can lift for a single full repetition of an exercise with proper form. It is the benchmark most strength programs are based on.