1RM calculator
Estimate your one-rep max from a hard set, then use it to set smarter starting loads for strength or hypertrophy work.
Enter a hard set to estimate your one-rep max.
Short answer
What this 1RM calculator is for
A one-rep max calculator estimates the heaviest weight you could lift for one rep based on a hard set you already performed. It is most useful when you want training percentages without testing a true max. Enter a recent set where the reps were clean, the range of motion was consistent, and you had no more than one or two reps left in reserve.
Treat the result as a planning number, not a promise. Fatigue, technique, exercise choice, equipment, and confidence all affect a true max attempt. For most lifters, the safer move is to estimate the max, choose conservative working weights, and let your logged training decide whether the next session should increase.
Epley formula
1RM = weight x (1 + reps / 30)Brzycki formula
1RM = weight x 36 / (37 - reps)How to use your estimate
Use the estimate as a reference point, not a dare. For strength work, many lifters train heavy sets around 75 to 88 percent of estimated max. For hypertrophy, the exact max matters less than keeping loads challenging and adding reps or weight over time.
Brace AI uses estimates like this as one input. Your logged sets, effort, and recent performance matter more than a single calculator result.
If your estimated max jumps after one unusually good set, do not rebuild the whole program around it immediately. Use the estimate to set a range, then confirm it over the next few workouts. A number that improves across multiple sessions is much more useful than a single optimistic calculation.
For main lifts, a conservative estimate can also help you choose warm-up jumps. If the calculator says your bench press is around 100kg, you do not need to train every work set near 100kg. You might use 70 to 80kg for repeatable volume, 82.5 to 90kg for heavier strength work, and save true max attempts for a planned test day when technique, sleep, and recovery are lined up.
If two formulas give noticeably different numbers, use the lower one for programming. A conservative estimate rarely ruins a training block; an inflated estimate can make every percentage set too heavy and slow down progress for weeks.
Why you should trust this
Use estimates conservatively
This calculator uses two common strength formulas instead of relying on a single equation. That smooths out some edge cases, but no formula can fully account for bar speed, skill, fatigue, depth, grip, equipment, or whether the set was truly close to failure.
How we picked the output: low-rep sets are weighted as more reliable, higher-rep sets should be treated cautiously, and the final number is best used for training zones rather than a risky max attempt. Last reviewed June 2026.
Common 1RM calculator mistakes
Using easy sets
A set with several reps in reserve will underestimate your max unless you account for the unused reps. Use a hard set, not a warm-up.
Using very high reps
Sets above 10 reps can drift because conditioning and pain tolerance start affecting the result more than max strength.
Changing technique
A touch-and-go bench, high squat, or hitched deadlift can inflate the estimate. Compare numbers only when the lift standard is consistent.
Let your coach do the math
Brace AI tracks every set and auto-progresses your loads, so you never open a calculator at the rack again.