One Rep Max Calculator
Enter any set you've done and get your estimated 1RM from four proven formulas, plus training percentages for programming your next block.
Enter a weight and reps (1 to 15) to see your estimated 1RM.
Frequently asked questions
How is my 1RM calculated?
Your set is run through four well-known formulas: Epley, Brzycki, Lombardi, and O'Conner. The headline number is the average of all four, and you can see each individual estimate in the table.
How accurate is an estimated 1RM?
Estimates are most accurate from sets of 2 to 6 reps. Above 10 reps the formulas start to diverge and accuracy drops. Treat the result as a programming guide rather than a guarantee of what you can lift for a single. For a deeper dive, read our guide to estimated 1RM.
What are the training percentages for?
Many programs prescribe weights as a percentage of your 1RM, for example 5 reps at 80%. The percentage table shows the weight at each common percentage along with roughly how many reps most lifters can manage there.
How do I track my 1RM over time?
Gym Note Plus estimates your 1RM automatically from every workout you log, so you can watch your strength trend upward without ever testing a true max. Just write your workout like a note and the app does the rest.