Use the One Rep Max Calculator to estimate a maximum from a completed set, compare the supported equations, or calculate loads from a known maximum. Keep the exercise and external-load convention consistent.
Reading a one-rep-max estimate
Enter the total external load and completed repetitions from one recorded repetition-maximum set. For a barbell, the load includes the bar and both plate stacks. Keep the exercise and counting convention consistent. An ordinary set stopped with repetitions remaining supplies different information; this tool does not correct for that difference. The default equation is Epley with the cited rounded coefficient. Calculation details show all three equation estimates, their range, percentages of the selected base and inverse repetition-load projections. The range is the spread between formulas, not a statistical confidence interval. The result estimates a maximum; it does not verify that you can complete the lift.
Do not sum repetitions across several sets or add bodyweight to the entered external load.
Choose a recorded set for estimation, or enter a known max when only arithmetic projections are needed.
Bench press worked example
The bench preset enters 185 for 5 completed repetitions. Epley returns 215.8025 . The same set gives 208.145815 with Brzycki and approximately 217.304504 with Lombardi.
Its custom 75% projection is 161.851875 . Rounding that custom projection to the nearest 2.5 gives 162.5 . The reference chart remains unrounded. These are calculated projections, not instructions to attempt those weights.
Percentages of an entered maximum
Illustrative arithmetic for an entered maximum of 100 . The calculator’s details generate the same percentage chart for your own selected or entered base.
| Share of entered base | Unrounded load |
|---|---|
| 50% | 50 |
| 60% | 60 |
| 70% | 70 |
| 75% | 75 |
| 80% | 80 |
| 85% | 85 |
| 90% | 90 |
| 95% | 95 |
| 100% | 100 |
These percentages are arithmetic reference points, not a training prescription or a guarantee of repetitions.
Why the equations give different estimates
With load w and repetition count r, the cited equations are Epley w × (1 + 0.0333 × r), Brzycki 100 × w ÷ (102.78 − 2.78 × r), and Lombardi w × r^0.1. Their different curves give different estimates from the same recorded set. The coefficient variant matters: the rounded Epley and Brzycki expressions here can differ slightly from tools using 1/30 or 36/(37 − r). The Canadian Strength and Conditioning Association’s Table 1 is the equation basis.
This calculator accepts whole repetition counts from 1 through 10 as a local scope limit. If the entered set contains a single repetition, every method returns the entered load under an explicit identity policy. This avoids extrapolating above a load already recorded as a single. The input range does not establish an accuracy guarantee, and formula agreement does not eliminate uncertainty from the set itself.
Lombardi’s fractional power is evaluated numerically. Its result is marked approximate, and displayed masses are rounded to at most six decimal places.
Known maxima and projected loads
The known-max preset uses an entered base of 100 . Its 80% projection is 80 . If you enter an already reduced training max, that value becomes the base exactly; no additional reduction is applied. Optional custom-load rounding uses the increment in the selected mass unit and rounds exact halfway cases upward.
The inverse preset uses a 100 maximum and the Brzycki equation for a five-repetition load. It returns 88.88 . This algebra reverses the same prediction curve; it does not establish how many repetitions you will actually complete.
Bench press, squat and deadlift estimates use the same one-set equations here. Equipment changes, weighted pull-ups and machine resistance can alter the meaning of an entered load; no bodyweight or machine adjustment is inferred. For arithmetic involving an arbitrary base, the Percentage Calculator solves the general percentage job. The Ratio Calculator handles proportional relationships independently of a maximum estimate.
Numeric inputs accept up to 64 characters and 20 decimal places. A decimal that changes when converted to the calculator’s numeric value is rejected. Rounding uses the accepted decimal values consistently.
When the next question is which matched plates produce a total, the Plate Loading Calculator uses the bar, collars and available pairs.
Recorded sets and repetitions can be summed as external tonnage in the Workout Volume Calculator; that total measures a different quantity from maximum load or plate counts.
For confirmed powerlifting performances compared through a quartic bodyweight adjustment, the DOTS Calculator names its coefficient basis and reports any source clamp.
For scores requiring the original or March 2020 revised Wilks protocol, the Wilks Calculator reports both named scales and their coefficient limits.