One Rep Max Calculator
A set of 225 lb for 5 clean reps estimates to a 262.5 lb one rep max with the Epley formula. This one rep max calculator estimates your 1RM from the weight you lifted, the reps you completed, and the unit you train in. It works for pounds or kilograms and gives you a fast way to turn a solid work set into a practical strength estimate. Use it when you want a planning number for bench press, squat, deadlift, overhead press, or another barbell or dumbbell lift without testing an all-out single that day. The estimate is most useful for programming, comparing training cycles, and setting rough percentage-based work such as 85% or 90% sets. It is not a promise of what you can safely lift today. Rep speed, exercise technique, fatigue, sleep, confidence, and setup quality all affect whether a true max attempt matches the estimate.
Quick answer
This calculator uses the Epley equation, which estimates one rep max as lifted weight multiplied by 1 plus reps divided by 30.
What this tells you
- •This calculator uses the Epley equation, which estimates one rep max as lifted weight multiplied by 1 plus reps divided by 30.
- •The estimate is usually most useful when the set comes from a lower rep range completed with consistent form and a real stopping point.
- •Very high-rep sets can inflate or distort the estimate because fatigue tolerance differs a lot from one lifter to another.
- •The result is best treated as a training reference for load selection, not as an instruction to attempt that exact number immediately.
How to Use
- 1Enter the weight you actually lifted for the set. Use the load on the bar or dumbbells only if that matches how you normally track training.
- 2Enter the number of completed reps. Count only reps done with the range of motion and control standard you would consider valid in your own program.
- 3Choose kilograms or pounds so the output matches your logbook, plates, and gym setup.
- 4Click calculate to view your estimated 1RM plus approximate 85% and 90% training loads.
- 5Use the result as a starting point for planning. If the number seems high compared with recent training, reduce it and base your next session on the more conservative load.
How It Works
Formula
Estimated 1RM = lifted weight x (1 + reps/30)The formula file for this tool uses the Epley method: oneRepMax = liftedWeight * (1 + reps / 30). In plain language, you start with the weight from a completed set and increase it by a fraction based on how many reps you performed. A 5-rep set adds 5/30, or about 16.67%, to the lifted weight. The tool also calculates 85% and 90% of the estimated max, which many lifters use as rough reference points for heavy but submaximal work. This method assumes the set reflects a meaningful effort with stable technique and falls inside the supported 1 to 15 rep range.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Bench press estimate from 100 kg for 5 reps
Using the Epley formula, 100 x (1 + 5/30) = 100 x 1.1667 = 116.67 kg after rounding. That does not mean 116.67 kg will be available on the bar the same day. It means a 5-rep set at 100 kg suggests your bench press max is roughly in that range under suitable conditions.
225 lb squat set for 5 reps
The math is 225 x (1 + 5/30) = 225 x 1.1667 = 262.5 lb. A lifter might use that estimate to choose future percentage work instead of guessing. For example, 90% would land around 236.25 lb in the tool's secondary results.
Deadlift estimate from 185 lb for 8 reps
Here the calculation is 185 x (1 + 8/30) = 185 x 1.2667 = 234.33 lb after rounding to two decimals. Because 8 reps sits higher than a typical peaking range, the number should be treated as a rough estimate rather than a precise meet-day prediction. It is still useful for tracking progress when you repeat similar work sets over time.
60 kg overhead press set for 10 reps
For this set, 60 x (1 + 10/30) = 60 x 1.3333 = 80 kg. The clean result makes the calculation easy to follow, but a 10-rep overhead press set can vary a lot with fatigue and rest. Use the estimate to guide future loading, then adjust if your actual singles move much slower or faster than expected.
140 kg front squat set for 3 reps
This time the formula gives 140 x (1 + 3/30) = 140 x 1.1 = 154 kg. Lower rep sets like triples often provide a steadier basis for 1RM estimation because they sit closer to true maximal strength. Even so, bar speed, depth, and fatigue still matter before treating 154 kg as an attempt selection.
165 lb bench press for 6 reps to set the next block's loads
Jordan wants working weights for a new bench program without testing a single. The set was 165 lb for 6 clean reps, so 165 x (1 + 6/30) = 165 x 1.2 = 198 lb. The tool's secondary results give 85% as 168.3 lb and 90% as 178.2 lb. On a bar loaded in 5 lb steps that means 165 lb for heavy sets of 6 and 175 lb for sets of 4, both rounded down to stay conservative.
Epley and Brzycki estimates for the same 100 kg set
Each row takes a set of 100 kg for the listed reps and estimates 1RM two ways. The last column is the percent of 1RM that the NSCA's training-load chart pairs with that rep count, shown next to the percent the Epley formula implies.
| Reps | Epley 1RM (this tool) | Brzycki 1RM | Epley implied % of 1RM | NSCA chart % of 1RM |
|---|---|---|---|---|
| 1 | 103.33 kg | 100.00 kg | 96.8% | 100% |
| 2 | 106.67 kg | 102.86 kg | 93.8% | 95% |
| 3 | 110.00 kg | 105.88 kg | 90.9% | 93% |
| 4 | 113.33 kg | 109.09 kg | 88.2% | 90% |
| 5 | 116.67 kg | 112.50 kg | 85.7% | 87% |
| 6 | 120.00 kg | 116.13 kg | 83.3% | 85% |
| 7 | 123.33 kg | 120.00 kg | 81.1% | 83% |
| 8 | 126.67 kg | 124.14 kg | 78.9% | 80% |
| 9 | 130.00 kg | 128.57 kg | 76.9% | 77% |
| 10 | 133.33 kg | 133.33 kg | 75.0% | 75% |
| 12 | 140.00 kg | 144.00 kg | 71.4% | 67% |
| 15 | 150.00 kg | 163.64 kg | 66.7% | 65% |
Epley (1985): 1RM = weight x (1 + reps / 30). Brzycki (1993, Journal of Physical Education, Recreation and Dance): 1RM = weight x 36 / (37 - reps). Both estimate columns are computed and rounded to two decimals. Chart percentages come from the NSCA's Essentials of Strength Training and Conditioning (Haff and Triplett, 4th edition). This calculator uses Epley only.
What a 1RM estimate is for
A one rep max estimate gives you a planning number without the risk and fatigue of testing a true single. Coaches use it to set percentage-based loads, compare training blocks, and track progress from ordinary work sets. A lifter who benches 165 lb for 6 reps in January and 175 lb for 6 reps in April can see the estimated max move from 198 lb to 210 lb without ever loading a max attempt.
Estimates diverge as reps climb because every formula assumes a fixed relationship between reps and percent of max, and that relationship is not fixed. In the table above, Epley and Brzycki agree exactly at 10 reps and stay within roughly 4 kg of each other from 2 to 9 reps, then split by nearly 14 kg at 15 reps. Fatigue tolerance, muscle-fiber makeup, and how close to failure the set really was all matter more at high reps, so two lifters with the same 12-rep set can have very different singles.
To program from the estimate, multiply it by the percent that matches the session's goal. This calculator already shows 85% and 90% of the estimated max. Using the 198 lb bench estimate, 85% is about 168 lb, which the NSCA chart pairs with sets of 6, and 90% is about 178 lb, paired with sets of 4. If the sets feel harder than the chart suggests, lower the estimate rather than the percentage, because the input set was probably not as maximal as assumed.
The formulas have limits worth knowing. Epley (1985) and Brzycki (1993, Journal of Physical Education, Recreation and Dance) were both published as practical rules, and Brzycki cautioned that his equation is meant for sets of about 10 reps or fewer. Validation work such as LeSuer et al. (1997, Journal of Strength and Conditioning Research) tested these formulas on bench press, squat, and deadlift in college-age men and women, and the estimates tracked bench press more closely than squat or deadlift. Accuracy drops with high-rep sets across this research, so treat any estimate from more than 10 reps as a rough guide.
Common mistakes
- Using a set with partial range of motion, bouncing, or obvious technique breakdown and expecting the estimate to reflect a clean competition-style max.
- Entering the wrong unit, such as typing pounds but leaving the selector on kilograms, which changes the result completely.
- Using a very high-rep grinder and assuming the estimate is just as reliable as a crisp triple or set of five.
- Treating the calculated 1RM as a guaranteed safe attempt instead of a planning estimate that still needs judgment.
- Ignoring context like fatigue, missed sleep, recent illness, or limited equipment when deciding whether to test a true max.
Limitations
This estimate depends on the Epley formula (1985) and a small set of inputs. Prediction equations like Epley and Brzycki (1993, Journal of Physical Education, Recreation and Dance) are simple rules that assume a fixed relationship between reps completed and percent of max, and validation studies such as LeSuer et al. (1997, Journal of Strength and Conditioning Research) have tested them mainly on bench press, squat, and deadlift in young adults, with bench press predicted more closely than the other two lifts. Brzycki advised limiting his equation to sets of about 10 reps or fewer, and accuracy for all of these formulas drops as reps rise, which is why this tool caps input at 15 reps. The formula does not account for exercise-specific skill, range of motion standards, tempo, fatigue from earlier sets, bodyweight changes, confidence under heavy singles, or differences between touch-and-go reps and paused or competition-standard reps. It also does not tell you whether a max attempt is appropriate for your current training phase. If your set quality was inconsistent or the rep count was very high, the estimate can drift away from what you would actually lift for one controlled rep.
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