Enter the weight and reps you just lifted to estimate your one-rep max.
| % of 1RM | Weight |
|---|
Your one-rep max (1RM) is the heaviest weight you can lift for a single full repetition of an exercise with correct form. Testing it directly is risky and fatiguing, so most lifters and coaches estimate it instead using a rep-max formula — this is how to calculate your one rep max without testing it against a true single-rep attempt. This calculator supports four established formulas: Epley, Brzycki, Lander, and Lombardi.
Enter the heaviest weight you lifted for a clean set, along with how many reps you completed before reaching failure. Choose a formula and unit, then calculate. For the most reliable estimate, use a set of 10 reps or fewer — accuracy drops for higher-rep sets. The result table below shows common training percentages so you can plan your next session's working weights directly.
Knowing your estimated one-rep max is just the baseline. To build an effective strength and hypertrophy program, you need to apply the correct percentage of your max to your working sets. Here is how to use your 1RM to hit your specific fitness goals without overtraining:
Not all one-rep max calculators are created equal. Because human biomechanics and fatigue rates vary, sports scientists have developed different mathematical models to estimate maximal strength. Here is a look at the four formulas used in this calculator:
1RM = Weight × (1 + Reps / 30)
The most widely used baseline in strength training. It assumes a
linear relationship between weight lifted and reps completed.
Best for: general strength estimates and heavy
compound movements (squat, deadlift) in the 1–10 rep range.
1RM = Weight × 36 / (37 − Reps)
Developed by Matt Brzycki, this hyperbolic equation is a gold standard
for powerlifters. As reps increase, it becomes increasingly
conservative to prevent overestimation. Best for:
heavy pressing movements (bench press, overhead press) in the 1–8 rep
range.
1RM = (100 × Weight) / (101.3 − 2.67123 × Reps)
A precise linear model that provides a stable average between
aggressive and conservative estimates. Best for:
moderate rep ranges (5–12 reps) and lifters wanting a realistic
working max without heavy CNS fatigue.
1RM = Weight × Reps^0.10
A non-linear power function that increases the estimated 1RM by
smaller increments as reps go up. Best for: athletes
with high muscular endurance calculating a max from higher-volume
sets (10+ reps).
It estimates the maximum weight you could lift once, based on a lighter weight lifted for multiple reps.
Different formulas can produce different estimates, especially at higher rep counts. Epley and Brzycki are most commonly used under 10 reps; Lombardi scales more gently for higher-rep sets. Treat any result as an estimate, not a guaranteed maximum.
Yes, but accuracy decreases as reps increase. Lombardi or Lander adjust for fatigue better in that range than Epley or Brzycki.
Yes, these are general-population formulas used for both men and women, though minor accuracy differences can appear at higher rep ranges.
For most lifters, estimating from a 3-5 rep max is safer and causes less CNS fatigue than testing a true max.