Training tool
One-rep max calculator
Estimate your 1RM from a recent set, then turn that estimate into a practical training-max reference. Useful for structured lifting blocks. Not a promise of a tested max.
Best for
For lifters using structured strength or hypertrophy programs who need a planning number without max testing every week.
Estimate from a recent set
Lower-rep sets usually make better inputs.
Use the load you actually lifted with the technique you want to compare over time.
This public calculator accepts 1-12 reps and caps RPE-adjusted reps at 12.
Estimated result
Enter a recent set.
The output will show formula spread, RPE/RIR adjustment, and a conservative training max.
No black box
Formula transparency
Protocol shows the formula spread instead of pretending there is one perfect estimate. Epley uses weight x (1 + reps / 30). Brzycki uses weight x 36 / (37 - reps).
The displayed Protocol estimate averages those two outputs when both are available. RPE is handled as a simple reps-in-reserve adjustment: RPE 10 means 0 reps left, RPE 9 means about 1 rep left, and so on.
Treat the result as a planning number. If your program uses a training max, keep it conservative and update it from repeatable sets, not one unusually good day.
Use it well
- Use a recent set with consistent technique, preferably lower reps, as the input.
- Compare formula outputs instead of treating one number as truth.
- Use the training max as a conservative anchor for planned percentages.
- Retest with the same movement standard so the trend means something.
Keep it honest
Caveats
- Estimated 1RM is a planning reference, not a tested max.
- Higher-rep sets, inconsistent tempo, form changes, fatigue, and exercise selection can distort estimates.
- Max testing needs appropriate setup, spotting, and experience.
Research trail
Sources
- Epley formula transparency
This page shows the exact Epley calculation used for the public estimate instead of hiding the math.
- Brzycki 1RM prediction paper
Primary paper describing prediction of one-rep max from reps-to-fatigue.
- Resistance-training RPE scale
RPE in resistance training is commonly anchored to reps in reserve.
- 1RM prediction limitations
Review context on factors that affect 1RM prediction and testing.
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