1RM calculator: estimate your max without testing it
Enter a set you did, read your estimated max and the loads to use for any number of reps. Epley and Brzycki formulas, warm-up ramp, and when a real max test is worth it.
Your 1RM is the heaviest load you can lift once, with proper form. You do not need to test it to know it: a set you already did is enough.
1
Enter the load
The load of a recent set, for example your last set of bench press.
2
Enter the reps
How many reps you completed with that load, from 1 to 12.
3
Read your max
Then the load table, to pick your next set.
1RM calculator
Enter a set you did recently: the load, and how many reps you completed with it (1 to 12).
Your estimated max for one rep
Example: 100 kg × 5 reps. Replace with your own set.
Which load for how many reps
Your program says "5 reps at 85 %"? Read the 85 % row: that is the load to put on the bar. The last column says how many reps people can usually do at that percentage.
| % of max | Load (kg) | Reps you can do |
|---|---|---|
| 100% | 117.5 | 1 |
| 95% | 110 | 2 |
| 90% | 105 | 4 |
| 85% | 100 | 6 |
| 80% | 92.5 | 8 |
| 75% | 87.5 | 10 |
| 70% | 82.5 | 12 |
| 65% | 75 | 15 |
| 60% | 70 | — |
| 55% | 65 | — |
| 50% | 57.5 | — |
These reps are an order of magnitude: they vary with the exercise and with you. Below 65 %, it depends more on endurance than on strength, so there is no number.
In the tables, loads are rounded to the plates you find in a gym (2.5 kg or 5 lb): the 100 % row can therefore differ slightly from the estimated max.
Your max for 1, 2, 3, 5, 8, 10 and 12 reps
The heaviest load you should be able to lift for that number of reps.
| Reps | Max load (kg) |
|---|---|
| 1 | 117.5 |
| 2 | 110 |
| 3 | 105 |
| 5 | 100 |
| 8 | 92.5 |
| 10 | 87.5 |
| 12 | 82.5 |
Warm-up before your set at 100 kg
Four light sets, getting heavier, before you start your working set.
- 50%5 reps50 kg
- 65%3 reps65 kg
- 80%2 reps80 kg
- 90%1 rep90 kg
How to read the results
The estimated max
The load you could lift once, based on your set. You do not need to test it to use it. One tip: enter a set of 3 to 6 reps, done hard but clean. That is where the estimate is most accurate.
The percentage table
Your program talks in "% of max"? This is it. As a rule, 8 reps happen around 80 %, 5 around 85 %, 3 around 90 %.
The max by reps
The same question the other way round. The plan says 3 reps: here is the load to put on the bar.
The warm-up
Four light sets, getting heavier, to reach your working set without a bad surprise.
Where these numbers come from
The calculator uses two classic formulas, Epley and Brzycki, and shows both.
- Epley: max = load × (1 + reps ÷ 30)
- Brzycki: max = load × 36 ÷ (37 − reps)
Up to 6 reps, they give almost the same result. Beyond that they drift apart a little: for a set of 12, the gap can reach 5 to 8 kg on a 100 kg lift. Neither one is right. The gap simply shows that the estimate gets less precise as the set gets longer. Past 10 reps you are measuring endurance more than strength, which is why the calculator stops at 12.
One habit: keep the same formula from one time to the next, so your numbers stay comparable.
Should you test your real max?
For training, no. An estimate is enough to choose your loads, see whether you progressed from one month to the next, or compare two exercises. A real max test only adds something if you compete, or if you prepared for it over a block and want to see what it produced.
If you are new to the movement, coming back from a break, or feeling anything unusual in a joint: keep the estimate, skip the test.
What next?
The number is only useful if it moves. Next session: same load and one more rep, or same reps and a small step up. That is progressive overload, and it starts with knowing what you did last time.
The reps you leave in the tank count too: a set of 5 stopped with two reps in reserve does not say the same thing about your max as a set of 5 taken to the limit. More on that here.
Once the load is chosen, it still has to go on the bar: the plate calculator tells you which plates to put on each side.
What the number does not tell you
An estimated max is one number for one exercise on one day. It moves with sleep, with what you ate, with the fatigue of the week. Two estimates a few kilos apart are the same estimate: look at the trend over several weeks, not at the difference between two sessions.
It also says nothing about the quality of the reps. A set of 5 where the last two were ground out with a rounded back gives the same number as a clean one, and only one of the two is worth building on.
Log your sets, and let the curve do the talking.