One Rep Max Calculator
Estimate your 1RM from a set you have actually done, compare the major formulas, and get your training percentages.
Your details
The load on the bar for the set you completed.
Clean reps to near failure. Estimates degrade badly above about ten.
This calculator runs entirely on your device. Nothing you enter is uploaded, stored, or sold. How this works
Estimated one rep max
259.1 lb
from 225 lb × 5 reps
Includes your inputs, the full breakdown, and every row of the table.
Epley
262.5 lb
Brzycki
253.1 lb
Lombardi
264.3 lb
Formula spread
11.2 lb
- Set performed
- 225 lb × 5
- Epley
- 262.5 lb
- Brzycki
- 253.1 lb
- Lombardi
- 264.3 lb
- O'Conner
- 253.1 lb
- Wathen
- 262.3 lb
- Average of all five
- 259.1 lb
| Intensity | Load | Typical reps |
|---|---|---|
| 100% | 259.1 lb | ~1 rep |
| 95% | 246.1 lb | ~2 reps |
| 90% | 233.2 lb | ~3 reps |
| 85% | 220.2 lb | ~5 reps |
| 80% | 207.3 lb | ~8 reps |
| 75% | 194.3 lb | ~10 reps |
What this means
- A 5-rep set is in the range where these formulas are most reliable — expect the estimate to land within a few percent of a true max.
- Every formula assumes the set was taken close to failure. If you left three reps in the tank, your real max is higher than this.
How the one rep max calculation works
A one rep max is the heaviest load you can move for a single clean repetition, and it is the number nearly every strength program is written around. Actually testing one is time-consuming, requires a spotter on most lifts, and leaves you too fatigued to train properly for days afterwards. Estimating it from a set you have already completed gives you the same programming information at no cost.
The five formulas here were each fitted to different populations and lifts, which is why they disagree. Epley and Brzycki are the two you will see most often and they cross over at ten reps — below that Brzycki reads lower, above it Brzycki climbs faster. Rather than picking a favourite, this calculator shows all five and averages them, because the spread between them is itself useful information about how much confidence the estimate deserves.
Accuracy falls off sharply as reps increase. At one to five reps the estimates are tight and genuinely useful. By fifteen reps you are measuring muscular endurance rather than maximal strength, and the relationship between the two varies enormously between individuals depending on muscle fibre composition and training history.
Frequently asked questions
Which one rep max formula is the most accurate?
None of them is reliably best across all lifts and people. Brzycki tends to be closer for low-rep sets and Epley for higher-rep sets, with the crossover around ten reps. Averaging several formulas, as this calculator does, is more robust than trusting any single one.
Why is my estimated max higher than what I can actually lift?
Usually because the set was not truly to failure, or because the lift is one where technique limits you before muscle does. Deadlifts and squats estimate reasonably well; bench press and especially overhead press often come in optimistic since grip, stability and bar path degrade under maximal load.
How often should I recalculate it?
Every four to eight weeks, or whenever a working set feels noticeably easier than the programme predicted. Recalculating from a heavy set of three to five is safer than testing an actual single and costs you nothing in recovery.
Should I train at my one rep max?
Rarely. Most strength gains come from work between seventy and ninety percent, where you can accumulate meaningful volume without the recovery cost and injury risk of true maximal singles. Testing a real max is a competition or peaking activity, not a training method.
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Disclaimer. This calculator is provided for general information and educational purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Results are estimates based on the inputs you provide and the assumptions described above. Confirm any figure with a qualified professional before acting on it.