A free one rep max calculator using the Epley, Brzycki and Lombardi formulas, with the weights to lift for every goal.
Estimate your one rep max from any set, and see what to lift for strength, size or endurance.
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These calculators give general estimates for healthy adults, not medical advice. Talk to your doctor before you change how you eat or train, especially if you're pregnant, take medication or have a health condition.
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This free one rep max calculator estimates the most you could lift once, from any set you've done. It uses three published formulas, Epley, Brzycki and Lombardi, and shows what to lift at every percentage for strength, size or endurance.
I built it because testing a true max is risky and tiring, and you rarely need to. A good set of 3 to 10 reps tells you almost as much.
Here's how the formulas work, how to train from your number, and when to trust it.
TL;DRKey takeaways
What is a one rep max calculator?
A one rep max calculator estimates your 1RM from a set of several reps. It saves you testing a true max, which needs a spotter and fresh legs.
Each formula turns weight and reps into a 1RM a little differently, so the calculator shows all three and their average.
How to use the one rep max calculator
You need the weight and the reps from a recent hard set.
Your numbers stay in this browser.
The three formulas
Each formula has its own shape, and they agree most at low reps.
| Formula | Equation |
|---|---|
| Epley (1985) | Weight × (1 + reps ÷ 30) |
| Brzycki (1993) | Weight × 36 ÷ (37 − reps) |
| Lombardi | Weight × reps^0.1 |
Here's what each gives for 100 kg at different reps.
- Epley
- 110
- Brzycki
- 105.9
- Lombardi
- 111.6
- Epley
- 116.7
- Brzycki
- 112.5
- Lombardi
- 117.5
- Epley
- 133.3
- Brzycki
- 133.3
- Lombardi
- 125.9
The further you go past 10 reps, the further apart they drift.
A worked example
Here's the example the calculator loads when you press Try an example.
You squat 85 kg for 5 reps. Epley says 99.2 kg, Brzycki 95.6 and Lombardi 99.8, an average of about 98 kg.
- Weight
- 87.5 kg
- Reps
- 3
- Best for
- Strength
- Weight
- 82.5 kg
- Reps
- 5
- Best for
- Strength
- Weight
- 77.5 kg
- Reps
- 8
- Best for
- Muscle size
- Weight
- 72.5 kg
- Reps
- 10
- Best for
- Muscle size
- Weight
- 67.5 kg
- Reps
- 13
- Best for
- Muscle size
The weights are rounded to 2.5 kg, the smallest jump most gyms have.
How to train from your 1RM
Your 1RM sets the weight for every goal.
Strength
Lift 85% and up for 1 to 6 reps, the range the NSCA gives for strength.
Muscle size
Lift 67% to 85% for 6 to 12 reps.
Muscular endurance
Lift under 67% for 12 reps or more.
Mistakes to avoid
These are the common ways a 1RM estimate misleads.
- Estimating from a set of 15 or more reps
- Counting reps with poor form
- Testing a true max without a spotter
- Training at 100% every session
Re-estimate every four to six weeks from a fresh hard set.
Strength for life
Strength is one of the best predictors of how well you age.
If you are strong, you live better.
The dead hang test and the sit to stand test check two other kinds of strength that matter as you age.
Who is the one rep max calculator for?
It's for anyone who lifts, from a first barbell to a meet, and these tools go with it.
- Protein calculator – for the protein your training needs
- Macro calculator – for eating to build muscle
- Body fat calculator – for tracking muscle against fat
- Dead hang test – for your grip strength
- Centenarian decathlon – for training for the life you want at 100
Estimate your max here, then build your next four weeks from the table.
More health calculators
Every health calculator reads the same "You", so you only enter yourself once.
| Calculator | What it answers |
|---|---|
| Macro calculator | How much protein, fat and carbs? |
| Body fat calculator | How much of me is fat? |
| Calories burned calculator | What did my workout burn? |
| BMR calculator | What do I burn at rest? |
More muscle raises your BMR, and the BMR calculator shows by how much.
Plan your health with your AI
Take your numbers further in
One Rep Max Calculator FAQs
Questions about the one rep max calculator? Here's what to know.
A one rep max calculator estimates the most you could lift once, from a set of several reps.
This free one shows the Epley, Brzycki and Lombardi formulas and their average.
Use a formula like Epley's: weight × (1 + reps ÷ 30).
For 85 kg × 5, that's about 99 kg.
They're all close under 10 reps.
Averaging the three smooths out their differences.
A hard set of 3 to 10 reps with good form gives the best estimate.
The NSCA uses 85% and up for strength, 67% to 85% for size, and under 67% for endurance.
Only with a spotter, good form and a proper warm-up.
Most lifters can train from the estimate.
Yes, switch to US units and the table rounds to 5 lb jumps.
Yes, download it as a CSV, or save it as a page or a PDF.
No, it's a general estimate for healthy adults.
Talk to your doctor before you change how you eat or train, especially if you're pregnant, take medication or have a health condition.
Yes, it's free with no login.
I did.
I'm Navid Moazzez, and I made the one rep max calculator as one of my free tools on navid.me.
More about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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