Written by Tyler DiGiovanni | BSBM
Fact checked by Sam Coleman, Co-Founder
FACT CHECKED
Calculating your 1-rep max (1RM) is an important step in any gym-goers arsenal. Besides being able to answer the inevitable “How much do you bench?” question, you’ll also be able to design effective workouts using the appropriate amount of weight to hit your weight room goals. So, instead of loading up as much weight as humanly possible on the bar and risking major injury, we prefer to use some simple math formulas to give an idea of how much weight we can toss around.
Below are seven of the most popular calculations for figuring out 1RM, each with its own pros and cons. Underneath that, we’ll go into more depth on how to use your 1RM to get the most out of your gym sessions.
1. Epley Formula
1RM = Weight × (1 + 0.0333 × Reps)
Pros
- Simple and straightforward
- Widely used and accepted in the fitness community
- Effective for moderate rep ranges (5-10 reps)
Cons
- Less accurate for very high or very low rep ranges
- May overestimate 1RM for beginners with less muscle endurance
Example
If you lift 100 lbs for 10 reps: 1RM = 100 × (1 + 0.0333 × 10) = 133 lbs
(Link for Epley Formula 1RM calculator)
2. Brzycki Formula
1RM = Weight × (36 / (37 − Reps)
Pros
- Easy to calculate
- Tends to be more accurate for higher rep ranges (up to 10 reps)
Cons
- May underestimate 1RM for very low rep ranges (1-3 reps)
- Less effective for individuals with exceptional muscle endurance
Example
If you lift 100 lbs for 10 reps: 1RM = 100 × (36 / (37 − 10)) = 128 lbs
(Link for Brzycki Formula 1RM calculator)
3. Lombardi Formula
1RM = Weight × Reps^0.10
Pros
- Simple power function calculation
- Useful for moderate to high rep ranges
Cons
- Less accurate for low rep ranges
- Can be complex without a calculator
Example
If you lift 100 lbs for 10 reps: 1RM = 100 × 10^0.10 = 129 lbs
(Link for Lombardi Formula 1RM calculator)
4. O'Connor Formula
1RM = Weight × (1 + 0.025 × Reps)
Pros
- Simple linear function
- Suitable for a wide range of rep counts
Cons
- May overestimate 1RM for low rep ranges
- Less accurate for individuals with high muscle endurance
Example
If you lift 100 lbs for 10 reps: 1RM = 100 × (1 + 0.025 × 10) = 125 lbs
(Link for O'Connor Formula 1RM calculator)
5. Wathan Formula
1RM = Weight × (48 / (48 − 0.022 × Reps)
Pros
- More nuanced calculation that adjusts for rep ranges
- Can be more accurate for moderate to high rep ranges
Cons
- Slightly more complex calculation
- May not be as intuitive without a calculator
Example
If you lift 100 lbs for 10 reps: 1RM = 100 × (48 / (48 − 0.022 × 10)) = 131 lbs
(Link for Wathan Formula 1RM calculator)
6. Lander’s Formula
1RM = Weight / (1.0278 − 0.0278 × Reps)
Pros
- Effective for a wide range of rep counts
- Provides a balance between overestimation and underestimation
Cons
- More complex to calculate manually
- May not be as accurate for extremely high or low rep ranges
Example
If you lift 100 lbs for 10 reps: 1RM = 100 / (1.0278 − 0.0278 × 10) = 125 lbs
(Link for Lander's Formula 1RM calculator)
7. Mayhew et al. Formula
1RM = Weight / (0.522 + 0.419 × e^(-0.055 × Reps)
Pros
- Takes into account fatigue associated with increased reps
- Can be more accurate for various rep ranges
Cons
- Most complex calculation
- Requires a calculator or spreadsheet for practical use
Example
If you lift 100 lbs for 10 reps: 1RM = 100 / (0.522 + 0.419 × e^(-0.055 × 10)) = 127 lbs
(Link for Mayhew Formula 1RM calculator)
What’s The Point of Finding Your 1RM?
Alright, so now you have seven different ways of finding out approximately what your top-end lift would be. What can you do with that information? Here are several important reasons for finding out your 1RM:
1. Baseline Measurement
Probably the most important reason to find your 1RM is to get a solid idea of your strength level. Once you know what the upper limits of your lifting power is, you can create a workout plan tailored to your specific abilities.
2. Progress Tracking
A great thing about going on a gym journey is seeing the results in the mirror. Unfortunately, you can’t see strength, so being able to test your 1RM can help you track improvements and where you might need to step it up a bit.
3. Load Determination
One of the biggest mysteries for most people starting out at the gym is figuring out how much weight they should be using. A great thing about knowing your 1RM is being able to use the correct percentage of your 1RM for different training goals. Here are our preferred ranges:
- Strength Training:
- Use 80-90% of 1RM for low-rep sets (1-5 reps) to maximize strength gains.
- Hypertrophy Training:
- Use 70-85% of 1RM for moderate-rep sets (6-12 reps) to promote muscle growth (hypertrophy).
- Endurance Training:
- Use 50-70% of 1RM for high-rep sets (12-20+ reps) to improve muscular endurance.
- Progressive Overload:
- Gradually increase the weight lifted based on the updated 1RM to continuously challenge yourself.
Example:
- Squat 1RM: 200 lbs
- Strength Phase: 3 sets of 3 reps at 85% of 1RM (170 lbs)
- Hypertrophy Phase: 4 sets of 8 reps at 75% of 1RM (150 lbs)
- Endurance Phase: 3 sets of 15 reps at 60% of 1RM (120 lbs)
4. Periodization
If you’ve ever looked up any workout programs, you’ve seen periodization. In short, periodization is using all of the elements (intensity, volume, rest periods, frequency, range of motion, exercise selection) in a certain way to augment your gains. Loads are specific to the individual, so knowing your specific 1RM will help structure training cycles that will benefit you the most.
5. Safety
You might’ve seen videos of strongmen benching 600lbs and thought, goals. Well, the flip side of that is the increased risk of injury. If you look at most powerlifting competitors, they have suffered some sort of serious injury (shoulder issues, torn pecs, etc). If you know your limits, you are less likely to go for a weight that you can’t handle, reducing the likelihood of hurting yourself.
Wrap Up
Choosing the right 1RM formula can depend on the context, the lifter's experience, and the specific rep ranges being used. Simpler formulas like Epley, Brzycki, O'Conner, and Lombardi are more accessible for quick calculations, while more complex formulas like Wathan, Lander, and Mayhew can provide better accuracy across a broader range of rep counts. Using multiple formulas and comparing results can also provide a more comprehensive estimate of your true 1RM.
Estimating your 1RM is an essential part of strength training that helps you understand your limits and plan your workouts more effectively. Only one thing left to do. Get stronger.
Tyler DiGiovanni
Author