One Rep Max Calculator
Estimate your one rep max and get training percentages.
Your lift
| % | Reps | Weight |
|---|---|---|
| 100% | 1 | 115.5 kg |
| 95% | 2 | 109.7 kg |
| 90% | 4 | 104 kg |
| 85% | 6 | 98.2 kg |
| 80% | 8 | 92.4 kg |
| 75% | 10 | 86.6 kg |
| 70% | 12 | 80.9 kg |
Your one rep max, or 1RM, is the heaviest weight you can lift for a single repetition of an exercise with good form. It is the anchor of smart strength training, because most well-designed programs set your working weights as a percentage of it.
Why 1RM matters
Progress in the gym comes from applying the right amount of load: heavy enough to challenge your muscles, but not so heavy that your form breaks down. Knowing your 1RM lets you dial that in precisely, and it gives you a single number to track as you get stronger over months.
How we estimate it
Testing a true one rep max is stressful and carries injury risk, so most lifters estimate it instead. Enter a weight and the number of reps you completed with it, and we project your 1RM using three established formulas: Epley, Brzycki, and Lombardi. The estimate is most accurate when you use a set of ten reps or fewer.
Training with percentages
Once you know your max, you can program by percentage. As a rough guide, heavy strength work sits around 85 to 95 percent, hypertrophy work around 67 to 80 percent, and endurance work below 67 percent. The percentage table on this page shows the load for each rep range.
Turn it into a program
Numbers only help if they become a plan. SmaartCoach builds full strength programs with the right sets, reps, loads, and week-to-week progression, then coaches you through each session so you keep getting stronger safely.
Frequently asked questions
What is a one rep max?
Your one rep max (1RM) is the most weight you can lift for a single rep of an exercise. It sets the reference for programming your training loads.
How is 1RM estimated?
From a set you can do for several reps, formulas like Epley and Brzycki project your single-rep max. Estimates are most accurate under about 10 reps.
Why use percentages of 1RM?
Programs prescribe loads as a percentage of your max, for example 80 percent for strength work. This keeps intensity consistent as you get stronger.
Is it safe to test a true 1RM?
Testing a real max carries injury risk and needs a spotter and good technique. Estimating from a submaximal set is safer for most lifters.
Sources
Reviewed against these authoritative references. Last updated August 2026.
- MedlinePlus, U.S. National Library of Medicine. Exercise and Physical Fitness
- U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans
- Journal of the International Society of Sports Nutrition. ISSN position stand: protein and exercise
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