ποΈ One Rep Max Calculator
Estimate your 1RM from any set with Epley, Brzycki and Lombardi, plus a full training table.
Estimated 1RM (average of 3 formulas)
These are estimates for planning and education only, not medical advice. Talk to a qualified professional before changing your training or health routine.
How to Use This Calculator
Enter the weight you lifted and the number of reps you completed, and the calculator estimates your one rep max with three classic formulas, averages them, and builds a percentage table you can train from.
Enter the weight you lifted on a hard working set, with clean form and full range of motion.
Enter the reps you completed. Sets of 3 to 8 reps give the most reliable estimate; 1 to 12 all work.
Pick kg or lb. The formulas are unitless ratios, so the answer comes back in the same units you entered.
Read your three estimates, the average, and the training table of percentages with rep guidance.
The Three Formulas
All three formulas estimate the same thing from different angles. Epley assumes each rep beyond the first costs you about 1/30 of your max, and it is the most common formula in gyms. Brzycki uses a steeper curve and usually lands a little lower than Epley for low reps. Lombardi raises the rep count to the power of 0.10, which tracks well across higher rep ranges. None of them is the truth: they are educated estimates. Showing all three plus the average makes the uncertainty visible instead of hiding it behind one false-precise number.
Worked Example
You bench 100 kg for 5 reps. Epley: 100 x (1 + 5/30) = 100 x 1.1667 = 116.7 kg. Brzycki: 100 x 36 / (37 - 5) = 3600 / 32 = 112.5 kg. Lombardi: 100 x 5^0.10 = 100 x 1.1746 = 117.5 kg. The average of the three is (116.7 + 112.5 + 117.5) / 3 = 115.6 kg. Your training table then starts at 95% of the Epley estimate, 110.8 kg, down through 50%, 58.3 kg. Notice the spread: the formulas disagree by 5 kg, which is normal and honest.
Using the Percentage Table
Program your lifts as percentages of your estimated 1RM. For maximal strength, work at 85 to 95 percent for sets of 1 to 5. For building size and strength together, 70 to 85 percent for sets of 6 to 12 is the sweet spot. Below 70 percent is technique and endurance territory, great for warm-ups and high-rep finishers. The rep ranges in the table are typical pairings, not laws: if you can hit 10 clean reps at 80 percent, your estimate was conservative and you should retest with a heavier set. Retest or recalculate every 4 to 6 weeks as your lifts climb.
Disclaimer
These are estimates for planning and education only, not medical advice. Talk to a qualified professional before changing your training or health routine.
Frequently Asked Questions
What is a one rep max?
Your one rep max (1RM) is the heaviest weight you can lift for a single clean repetition of an exercise. Trainers use it as the baseline for programming: a set at 80 percent of your 1RM is a precise, repeatable training load. Testing a true 1RM is fatiguing and risky, so calculators estimate it from a lighter set you already did, which is safer and nearly as useful for programming.
Which 1RM formula is most accurate?
No formula is perfect, but Epley and Brzycki agree closely for sets of 1 to 10 reps, and both lose accuracy past 12 reps. Epley tends to slightly overestimate for low reps, Brzycki slightly underestimates, and Lombardi (which uses r^0.10) tracks well for higher rep sets. This calculator shows all three plus the average, so you can see the spread instead of trusting one number blindly.
How many reps should I use to estimate my 1RM?
Sets of 3 to 8 reps give the most reliable estimates, because the relationship between reps and max strength is tightest there. A set of 10 still works. A set of 12 or more introduces noise from muscular endurance, so treat those estimates as rough. Always use a set where the last rep was genuinely hard.
How do I use the percentage table in training?
Most strength programs prescribe loads as percentages of your 1RM: 85 to 95 percent builds maximal strength (1 to 5 reps), 70 to 85 percent builds strength and size (6 to 12 reps), and below 70 percent is endurance and technique work (12+ reps). Warm up through the lower percentages, then work at the prescribed load for the programmed reps.
Is it safe to test my true 1RM?
True 1RM testing carries real injury risk and is usually reserved for experienced lifters preparing for competition. Safer alternatives are submaximal rep tests (a heavy set of 3 to 5 reps) fed into this calculator, or simply tracking your working weights over time. Never attempt a true max without a spotter, safety pins, and a proper warm-up.