Key Takeaways
- A 3-rep max is roughly 93% of a 1RM, making it a practical near-max reference that is often used in strength programming.[1][4]
- This calculator uses 6 established formulas (Epley, Brzycki, Lombardi, Lander, Mayhew, Wathan) and shows the range so you can see how tight the estimate is.[2][3]
- Lower-rep input sets produce tighter estimates than higher-rep sets. If your recent set was 2-6 reps, the 3RM estimate is typically more consistent across formulas.[5]
- Use the 3RM as a journaling reference for near-max programming cycles, not as an absolute weight target.
What Is a 3RM?
A three-repetition maximum is the most weight you could lift for exactly 3 completed reps in a given exercise. Compared to a single (1RM), a 3RM test generally involves a slightly lower weight but still sits in the near-max intensity zone.[1]
Many strength programs prescribe 3-rep sets for intensity blocks. Having a logged 3RM reference helps you choose starting weights, plan progressions, and compare performance over time.
How the Estimation Works
The calculator first estimates your 1RM using each of the 6 formulas, then multiplies by approximately 0.9327 (the standard 3RM percentage factor) to derive the 3-rep weight.[2][4]
The percentage table below the main result shows how the estimated 1RM maps to other common rep ranges, with the 3-rep row highlighted for quick reference.
Why Formulas Give Different Numbers
Each formula was derived from different populations and exercises. Epley and Brzycki are the most widely referenced, while Lombardi, Lander, Mayhew, and Wathan offer alternative curve shapes. The spread between them tends to widen as input reps increase.[3][6]
Showing all 6 lets you decide how much confidence to place in the result. A tight cluster means the estimate is more consistent; a wide spread suggests using a conservative number for planning.
Rep-Max Percentage Reference
The percentage table is a standard reference used in strength programming. It maps each rep count to a percentage of the estimated 1RM so you can see how the 3RM fits within the broader spectrum from singles to higher-rep sets.
| Reps | % of 1RM |
|---|---|
| 1 rep | 100% |
| 2 reps | 97% |
| 3 reps | ~93% |
| 4 reps | 90% |
| 5 reps | ~87% |
| 6 reps | ~83% |
| 8 reps | ~79% |
| 10 reps | ~74% |
| 12 reps | ~71% |
| 15 reps | ~68% |
Practical Use for Logging
A 3RM estimate is most useful when paired with the date, exercise, and the actual set you used to generate it. This gives you a journaling snapshot you can compare against future performance.
If you are starting a new intensity block that calls for 3-rep sets, this number gives you a reference starting point. Adjust based on how the actual sets feel during your sessions.
Frequently Asked Questions
Sources & References
- Comparing One Repetition Maximum and Three Repetition Maximum Between Conventional and Eccentrically Loaded Deadlifts. Kelly SB, Brown LE, Coburn JW, Zinder SM, Gardner LM, Nguyen D. Journal of Strength and Conditioning Research (2015)
- Reliability of the One-Repetition Maximum Test Based on Muscle Group and Gender. LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. Journal of Sports Science and Medicine (2013)
- Test-Retest Reliability of the One-Repetition Maximum (1RM) Strength Assessment: a Systematic Review. Grgic J, Lazinica B, Schoenfeld BJ, Pedisic Z. Sports Medicine - Open (2020)
- Between-Participant Variability in Repetitions Completed at Given Intensities in Resistance Exercises: A Meta-Regression. Vieira AF, et al.. Sports Medicine (2024)
- Determination and Prediction of One Repetition Maximum (1RM): Safety Considerations. Kraemer WJ, Fry AC. NSCA Conference Proceedings (1995)
- Development of 1RM Prediction Equations for Bench Press in Moderately Trained Men. Macht JW, Abel MG, Mullineaux DR, Yates JW. Journal of Strength and Conditioning Research (2016)
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This tool is for informational and journaling purposes only.
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