One Rep Max Calculator
Enter the weight and reps of a set to estimate your one rep max (1RM) with the Epley, Brzycki and four other formulas, an optional RPE and training percentages. How it works
Use the One Rep Max Calculator
About the One Rep Max Calculator
From 135 lb × 5 reps, the estimated one rep max is 155 lb. That is the calculator’s default, the average of the Epley formula, weight × (1 + reps ÷ 30), which gives 158, and the Brzycki formula, weight ÷ (1.0278 − 0.0278 × reps), which gives 152. Four more formulas and the average of all six are shown beside it.
Estimated 1RM from a set with 100 (lb or kg), by reps and formula
| Reps | Epley + Brzycki (default) | Epley | Brzycki | Lombardi | Mayhew | O’Conner | Wathan | Average of 6 |
|---|---|---|---|---|---|---|---|---|
| 1 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| 2 | 105 | 107 | 103 | 107 | 111 | 105 | 105 | 106 |
| 3 | 108 | 110 | 106 | 112 | 114 | 108 | 109 | 110 |
| 4 | 111 | 113 | 109 | 115 | 117 | 110 | 113 | 113 |
| 5 | 115 | 117 | 113 | 117 | 119 | 113 | 117 | 116 |
| 6 | 118 | 120 | 116 | 120 | 121 | 115 | 120 | 119 |
| 7 | 122 | 123 | 120 | 121 | 124 | 118 | 124 | 122 |
| 8 | 125 | 127 | 124 | 123 | 126 | 120 | 128 | 125 |
| 9 | 129 | 130 | 129 | 125 | 129 | 123 | 131 | 128 |
| 10 | 133 | 133 | 133 | 126 | 131 | 125 | 135 | 131 |
| 11 | 138 | 137 | 139 | 127 | 133 | 127 | 138 | 134 |
| 12 | 142 | 140 | 144 | 128 | 135 | 130 | 141 | 137 |
Whole numbers, as the calculator shows them. Because the set is 100, each cell is also roughly the percentage to multiply your own weight by: 5 reps with 80 kg is about 80 × 1.15 = 92 kg by the default. For one rep every formula returns the weight itself.
Training percentages for a 155 lb one rep max (135 lb × 5 reps)
| Percent of 1RM | Weight (lb) | Reps to failure (default formula) |
|---|---|---|
| 95% | 147 | about 2 reps |
| 90% | 140 | about 4 reps |
| 85% | 132 | about 6 reps |
| 80% | 124 | about 8 reps |
| 75% | 116 | about 10 reps |
| 70% | 109 | about 12 reps |
| 65% | 101 | about 14 reps |
| 60% | 93 | over 15 reps |
| 55% | 85 | over 15 reps |
| 50% | 78 | over 15 reps |
The calculator multiplies the rounded headline estimate by each percentage and rounds to a whole number. The reps are the default formula read backwards: the reps at which the Epley and Brzycki average reaches 100 ÷ percent times the load. Under Epley alone 85% is about 5 reps and 70% about 13.
Loads by training goal in the ACSM position stand (2009), with the matching percent of 1RM
| Goal | ACSM loading | Percent of 1RM by the default formula |
|---|---|---|
| Strength, novice | 8 to 12 RM | 80% to 70% |
| Strength, intermediate and advanced | 1 to 12 RM, periodized, with emphasis on heavy 1 to 6 RM loads; 3 to 5 min rest | 100% to 70%; 1 to 6 RM is 100% to 85% |
| Hypertrophy | 1 to 12 RM, periodized, with emphasis on 6 to 12 RM; 1 to 2 min rest | 85% to 70% for 6 to 12 RM |
| Power | Light loads moved fast: 0 to 60% of 1RM for lower-body and 30 to 60% for upper-body exercises; 3 to 5 min rest | Given as percent of 1RM |
| Local muscular endurance | 40 to 60% of 1RM for more than 15 reps; under 90 s rest | Given as percent of 1RM |
RM is a repetition maximum: the heaviest load you can lift that many times. The position stand gives most loads as RM zones; the third column converts them with this calculator’s default formula (100 ÷ the Epley and Brzycki multiplier), rounded to the whole percent.
Methodology
The six formulas are listed under “The six formulas” on this page. The default headline is the mean of Epley and Brzycki, and you can switch it to any single formula or to the average of all six. With an RPE selected, the reps become reps + (10 − RPE) before any formula runs. Results are rounded to a whole lb or kg.
How to use this tool
- Enter the weight you lifted and pick lbs or kg. Switching the unit shows the weight in the other unit and leaves the number you typed unchanged.
- Enter the reps you completed, from 1 to 15. Above 10 reps, counting any reps in reserve, the calculator warns that estimates get unreliable, and above 15 it gives none.
- Leave RPE at None if the set went to failure. Otherwise pick an RPE from 6 to 10: RPE 8 means about 2 reps were left, so 5 reps at RPE 8 are treated as 7.
- Keep the Epley and Brzycki average as the headline, or pick one formula or the average of all six.
Frequently asked questions
- How do I calculate my 1RM from 5 reps?
- Multiply the weight by about 1.15. At 5 reps Epley gives weight × 1.167 and Brzycki gives weight × 1.125, and the calculator’s default is their average. So 225 lb × 5 comes out at 258 lb and 100 kg × 5 at 115 kg.
- Which 1RM formula is the most accurate?
- None is reliably best. A study that tested seven prediction equations on 67 untrained college students found correlations above 0.95 with the lifts they actually achieved, but most equations were off on average for the bench press and squat, and all of them underestimated the deadlift. The calculator shows six formulas side by side with the spread between them, so you can see how much they disagree for your set.
- How many reps can I use to estimate a one rep max?
- Up to 15 here, and fewer is better. For a set of 12 with 100 the six formulas range from 128 to 144, against 113 to 119 for a set of 5. A study of 70 adults on the bench press and leg press found that 5-rep sets predicted 1RM best and concluded that no more than 10 reps should be used with linear equations. The calculator warns above 10 reps to failure, which includes the reps in reserve you enter with an RPE.
- What does RPE do in a 1RM calculator?
- It adds the reps you had left. On the repetitions-in-reserve scale RPE 10 means none were left, RPE 9 means one and RPE 8 means two. The calculator adds 10 − RPE to your reps and runs the formula on the total: 135 lb × 5 at RPE 8 is treated as 135 × 7 and gives 164 lb instead of 155.
- What are the training percentages for?
- They are the rounded estimate multiplied by 95% down to 50% in steps of 5. For a 155 lb estimate, 80% is 124 lb and 70% is 109 lb. Programs that prescribe work as a percentage of 1RM use these numbers. Under each tile the calculator shows about how many reps to failure that load allows: about 8 at 80% and 12 at 70% with the default formula.
- What percentage of my 1RM should I lift for strength or muscle size?
- The ACSM position stand on resistance training (2009) gives loads as rep maximums: 8 to 12 RM for novices, 1 to 12 RM for experienced lifters with emphasis on 1 to 6 RM for strength and 6 to 12 RM for muscle size. By this calculator’s default formula 6 RM is about 85% of 1RM, 8 RM 80% and 12 RM 70%. For muscular endurance the stand gives 40 to 60% of 1RM for more than 15 reps.
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