OKTO How to calculate your one-rep max (1RM)
Enter the load you lifted and the reps you did to failure: the calculator estimates your 1RM with the Epley and Brzycki formulas. For example, 225 lb lifted 5 times gives a 1RM of about 257.8 lb.
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these calculations are built into OKTO fit, for every client
- The 1RM is saved as the client's record for the chosen exercise.
- In the program, an exercise's load comes straight from that record, from 60 to 90%.
- Age, sex, height and weight come from the client's file.
- Seven calculators with their sources: calories, one-rep max, heart rate zones, body fat percentage, water and protein, load progression and BMI.
Nothing is saved to the file without the client's health consent. OKTO Fit costs $29.99 a month plus taxes, no matter how many clients you have.
how the calculation works
Both formulas start from a set taken to failure and estimate the load you could lift once.
Epley: load × (1 + reps / 30)
Brzycki: load × 36 / (37 - reps)
With 225 lb lifted 5 times, Epley gives 262.5 lb and Brzycki 253.1 lb. The average, 257.8 lb, is the default. A single rep is the load itself.
The tables run the formula in reverse: they give the load to use for a number of reps or a percentage of your 1RM, rounded to 2.5 kg or 5 lb. These are the same formulas and the same rounding as in OKTO Fit, so you get the same number.
its limits
- It's an estimate. Your real 1RM may be a little higher or lower.
- Past 10 reps, the estimate becomes less reliable.
- The set has to go to failure with good form. A set stopped too early underestimates your 1RM.
- The result applies to one exercise at a time: your squat 1RM says nothing about your bench press.
sources
- Epley B. Poundage Chart. Boyd Epley Workout, Lincoln (Nebraska), Body Enterprises, 1985.
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD, 1993, 64(1), 88-90. doi.org/10.1080/07303084.1993.10606684
Estimate only. This is not medical advice. Before a maximal effort, especially after an injury or a long break, talk to a doctor or a kinesiologist.
frequently asked questions
What is a one-rep max (1RM)?
It's the heaviest load you can lift once, with good form, on a given exercise. You estimate it from a lighter set taken to failure.
Epley or Brzycki: which formula should I use?
Both give the same result at 10 reps. Under 10 reps, Brzycki comes out a little lower than Epley. The average of the two, used by default, splits the difference.
How many reps should I do to estimate my 1RM?
One heavy set of 10 reps or fewer, taken to the point where one more rep with good form isn't possible. Past 10 reps, the estimate becomes less reliable.
Should I test my real 1RM?
Not to build a program: the estimate is enough to pick your loads. A real test needs a proper warm-up, a spotter and experience. For a beginner, the estimate is the safe choice.
How many calories do you need per day?Our calorie calculator gives your total expenditure and macros, in kg or lb.
Calculate my caloriesyour clients, their records, their loads
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