One Rep Max Calculator
Estimate your 1RM from a set you already lifted, and see a full percentage chart for training.
This runs entirely in your browser. Nothing you type is uploaded anywhere.
How to use this tool
Pick a recent working set where you stopped close to failure, then enter the weight you lifted and how many clean reps you completed. Choose your unit (pounds or kilograms) and a formula, then press Calculate 1RM. The tool returns your estimated 1RM and a lifting max chart from 95 percent all the way down to 50 percent, so you can plan every training weight off a single number. Use the Copy result button to paste the chart into your training log.
The formula behind the one rep max calculator
Brzycki: 1RM = w × 36 / (37 − reps)
Both methods estimate the most weight you could lift for a single rep from a set of multiple reps. The Epley formula scales the weight up by the number of reps, so more reps means a higher estimate. The Brzycki formula uses a fixed lookup based on reps and tends to read slightly lower at higher rep counts. Neither is exact, but for the common 3 to 8 rep range they land very close to each other, which is why coaches trust them for programming. A single rep always returns the weight itself, since one rep already is your max for that set.
A real example
Say you bench pressed 185 pounds for 5 reps and stopped with little left in the tank. Using Epley: 1RM = 185 × (1 + 5 / 30) = 185 × 1.1667 = about 216 pounds. Using Brzycki: 1RM = 185 × 36 / (37 − 5) = 6660 / 32 = about 208 pounds. So your estimated bench press max sits in the 208 to 216 pound range. From the chart, an 80 percent training weight off the Epley number would be roughly 173 pounds for sets of 6 to 8 reps.
Common questions
How accurate is an estimated 1RM?
For sets under about 8 reps it is usually within a few percent of a true tested max. Accuracy drops as reps climb past 10, because fatigue and pacing affect how many reps you can grind out. For the best estimate, use a hard set of 3 to 6 reps.
Should I use Epley or Brzycki?
Either works well. Epley tends to read a little higher and Brzycki a little lower at higher reps. Many lifters run both and use the average. Pick one and stay consistent so your progress comparisons stay fair over time.
What is the percentage chart for?
Most strength programs prescribe training loads as a percent of your max, such as 5 sets of 5 at 80 percent. The chart turns your estimated 1RM into actual weights for every common percentage, so you can load the bar without doing the math each session.
Does this work for any lift?
Yes. The formulas apply to bench press, squat, deadlift, overhead press, and most barbell lifts. The bench press max chart label is just the most common use. Enter the weight and reps for whatever movement you tested.
Is it safe to actually attempt my calculated max?
Treat the number as an estimate for programming, not a target to chase blindly. If you do test a true max, warm up thoroughly and use a spotter or safety bars. This lifting max calculator is for educational use and is not a substitute for coaching or medical advice.