1RM calculator
Your 1RM (one-rep max) is the heaviest load you can lift once on an exercise. It is the reference for calibrating your sessions: most programs express their loads as a percentage of 1RM. Rather than testing a true max — tiring and risky — this tool estimates it from a submaximal set.
Enter a weight and a rep count between 1 and 12 (the estimate loses accuracy beyond that).
How the calculation works
The tool combines two proven formulas, Epley's and Brzycki's, and averages them to smooth out their differences. From the weight lifted and the reps performed, it projects the load you could lift just once.
The estimate is most reliable between 1 and 6 reps. Beyond 10-12 reps, endurance and technique take over from pure strength, and the projection becomes approximate: treat the result as a ballpark then.
What the 1RM is for
Knowing your 1RM lets you pick the right load for your goal: around 85-95% for strength, 70-80% for hypertrophy, below 70% for endurance. The load table above gives you these markers directly.
It is also an excellent progress indicator: if your estimated 1RM climbs month after month, you are simply getting stronger. Log your performances to track this curve over time.
Turning your 1RM into working loads
The main use of your 1RM is to set your working loads as percentages. Once your max is estimated, the load table gives you the weight for each zone directly: around 90% for strength on 3-4 reps, 75-80% for hypertrophy on 8-12 reps, and 65% or less for volume and technique.
These percentages are not rigid: your daily form, sleep and recovery change what you can actually lift. Adjust by feel, and recompute your 1RM every few weeks so your loads track your progress.
Frequently asked questions
Is the estimate accurate?expand_more
It is very reliable on short sets (1 to 6 reps), within a few percent. The more reps, the greater the uncertainty. Use it as a guide, not an absolute truth, and refine it with experience.
Should I test my true 1RM in the gym?expand_more
It is not necessary to progress, and it is discouraged for beginners: a true max demands perfect technique and a spotter. Estimating from a set of 3 to 5 reps is far safer day to day.
How often should I recompute my 1RM?expand_more
Every 4 to 6 weeks is enough for most trainees: that is how long it takes for strength to change measurably. Recompute from a solid recent set rather than attempting a true max.
Is the 1RM the same on every exercise?expand_more
No, it is specific to each lift: your deadlift 1RM will be far higher than your bench press. Estimate it lift by lift, on the movements where you track your progress.
Epley or Brzycki: which formula is more reliable?expand_more
Both are very close on short sets, which is why the tool averages them. Brzycki tends to give a slightly lower figure beyond 10 reps; on 1 to 5 reps the difference is negligible.
Track your progress, not just your calculations
Log your workouts, loads and weight, and watch your curve climb — for free.