1RM Calculator: One-Rep-Max and Training Percentages
Enter a weight and the reps you hit, and this estimates your one-rep max, then gives you the full percentage table to program from. Each working weight is rounded to the nearest 2.5, the smallest jump most plate sets can make.
How it works
A one-rep max is the most weight you can lift for a single rep. You rarely test it directly, so this estimates it from a set you already did. Enter the weight and reps, and the calculator applies a strength formula, then builds a percentage table so you can program a 5x5, a linear progression, or any percentage-based plan. The estimate is most accurate at low reps. Above about ten reps, fatigue and technique vary too much for any formula to be precise, so treat high-rep estimates as a rough guide. Once you have your working weight, the plate calculator loads the bar for you.
Common one-rep-max questions
How accurate is a 1RM calculator
Estimates are close at 1 to 5 reps and get less reliable above 10, because fatigue and form vary. Use it as a programming guide, not a tested max.
What percentage of my max should I train at
Strength work usually sits at 80 to 95 percent for low reps, hypertrophy at 65 to 80 percent for moderate reps, and technique or warmups below 60 percent.
How do I calculate my max without testing it
Do a set close to failure at a known weight, enter the weight and reps here, and the formula estimates the single-rep number.
How many reps give an accurate estimate
Aim for a set of 3 to 6 reps taken near failure. Fewer reps means a more accurate estimate.
The formulas
All three estimate the same thing from a weight and rep count, and they agree closely at low reps. Epley is the common default. Brzycki tends to read slightly lower at high reps. Lombardi uses a power curve. The calculator lets you switch and compare.
| Formula | Reads |
|---|---|
| Epley | weight times (1 plus reps divided by 30) |
| Brzycki | weight times 36 divided by (37 minus reps) |
| Lombardi | weight times reps to the 0.10 power |
Need to load the result on a bar? Use the plate loading calculator. Percentage work only lands if your plates actually weigh what the label says, so a 2.5 that is really 3 throws off every set. That is why we weigh every plate and publish the real number in the Basalt Ledger. See 1 inch vs 2 inch bars and plates, then shop plates.