StrengthPeaking.com
One Rep Max Calculator
Estimate your one-rep max for bench press, squat, deadlift, overhead press and other strength lifts.
Estimated One-Rep Max: 99.8kg for 80.0kg x 8 reps
Est One-Rep Max
Estimated rep maxes
2RM to 10RM
Estimated RPE & RIR chart
Singles
Important: The RPE & RIR chart is calculated using standard percentage-based RPE estimates applied to your calculated 1RM. As this uses a different model than the estimated rep maxes above, some values may vary slightly.
Want rep targets from this estimate? Use our One Rep Max Chart to estimate 2RM to 10RM training weights from your calculated max.
What Your 1RM Estimate Means
Use this estimate as a practical training max rather than an exact prediction. If the original set was very high-rep, very easy, or affected by poor technique, the estimate may be less reliable.
Formula Breakdown
Different one-rep max formulas can produce slightly different results. This calculator averages your selected formulas to give a balanced estimated 1RM.
About This 1RM Calculator
Estimate your one-rep max from a weight and rep count.
- Enter the weight lifted.
- Choose kg or lbs.
- Enter the reps completed.
- Calculate your estimated 1RM.
For best accuracy, use a hard but controlled set between 2 and 10 reps.
Your preferred unit is remembered, and results can be shared or copied.
About this 1RM Calculator
Learn how it works
What Is a 1RM Calculator?
A 1RM calculator estimates the heaviest weight you could likely lift for one repetition based on a recent set performed for multiple reps.
Instead of testing a true maximum in the gym, you enter the weight lifted and the number of reps completed. The calculator then estimates your one-rep max using several recognised prediction formulas.
Which Lifts Can You Use This For?
This calculator can be used for bench press, squat, deadlift, overhead press, rows, weighted pull-ups and most compound strength exercises.
For best results, use a challenging set of around 2 to 10 reps with consistent technique.
- Bench press and other pressing movements
- Back squat, front squat and lower-body strength lifts
- Deadlift variations including conventional and sumo
- Overhead press and strict shoulder pressing
How the Estimate Is Calculated
Different 1RM formulas can give slightly different results, especially when reps get higher. This calculator lets you compare multiple formulas and uses the average of your selected formulas as the main estimate.
Lower-rep sets are usually more reliable than high-rep sets because endurance, pacing and technique breakdown have less influence on the result.
Estimate Your One-Rep Max for Any Major Lift
For example, if you bench press 100kg for 5 reps, this calculator can estimate your one-rep max.
You can calculate your estimate in kg or lbs, compare multiple 1RM formulas and use the result to plan percentage-based training.
Try Common 1RM Calculations
Open a ready-filled example to see the estimated one-rep max, formula comparison, 2RM to 10RM estimates and RPE/RIR chart.
How Accurate Is a One-Rep Max Calculator?
A one-rep max calculator gives an estimate, not a guarantee. Your actual max can vary depending on fatigue, recovery, technique, confidence, equipment and how close the original set was to failure.
Most lifters get the most useful estimates from hard sets between 2 and 10 reps.
How to Use Your Estimated 1RM
Your estimated 1RM can help you choose training weights without needing to test a true maximum every week.
Many strength programmes use percentages of a one-rep max to plan volume, heavy work and peaking phases.
- Use 70–80% for volume and technique work
- Use 80–90% for heavier strength sets
- Use 90%+ sparingly for singles, peaking or testing
- Recalculate every few weeks using recent training performance
Bench, Squat, Deadlift and Overhead Press 1RM Estimates
You can use this one rep max calculator for bench press, squat, deadlift, overhead press and most compound strength lifts. For the most useful estimate, use the same lift variation you want to track over time.
- Bench press: use consistent paused or touch-and-go reps, and do not count reps helped by a spotter.
- Squat: compare the same squat variation, bar position and depth when tracking progress.
- Deadlift: avoid mixing conventional, sumo, block pulls and rack pulls when comparing estimates.
- Overhead press: use strict reps if you want a strict press estimate; push press reps will usually estimate higher.
Common 1RM Questions
What is a 1RM calculator?
A 1RM calculator estimates the maximum weight you could lift for one repetition based on a weight and rep count from a recent set.
Is a calculated 1RM the same as a true max?
No. A calculated 1RM is an estimate. A true max is tested directly with a single maximal repetition.
What rep range gives the best 1RM estimate?
Sets of around 2 to 10 reps usually give the most useful estimates. Very high-rep sets are more likely to overestimate or underestimate your true max.
Can I use this calculator for kg and lbs?
Yes. You can enter weights in kilograms or pounds and switch between units.
Which 1RM formula should I use?
No single formula is perfect for every person or lift. Comparing multiple formulas gives a more useful range.
Can I use my result with a one rep max chart?
Yes. After estimating your 1RM, you can use the One Rep Max Chart to estimate 2RM to 10RM training weights from that max.