Calculator
Estimate your 1RM, compare formulas, then choose a better rest interval
This tool turns a recent working set into an estimated max, maps that intensity to the rest strategy most likely to preserve performance, and shows your working weights from 50 to 100 percent.
Estimated 1RM
262.5 lb
Calculated with the Epley formula.
Relative intensity
85.7%
Based on the relationship between the set and the active formula estimate.
Suggested rest strategy
Use the 3 minute preset for heavy strength work
This set sits in a high-intensity range where ATP and neural recovery matter more than keeping metabolic stress high.
Working weights
Percentage table
50% to 100% in 5% steps
Frequently Asked Questions
How do you calculate your one-rep max?
The common approach is a formula applied to a set you actually completed. Epley estimates your max as weight multiplied by one plus reps divided by 30. For 100 kg for 5 reps that gives about 117 kg. Formulas are most accurate under about 8 reps, and drift upward beyond that.
How accurate are 1RM calculators?
Reasonably accurate within 1 to 8 reps, typically inside 5% of a tested max for trained lifters. Accuracy falls with higher rep sets, because endurance and fatigue resistance start influencing the result more than pure strength does.
Should I test my true one-rep max?
Rarely. A true max test is fatiguing, carries more injury risk, and needs its own recovery. Estimating from a 3 to 5 rep set gives you a number accurate enough for programming without the cost, which is why most lifters only test when peaking for a meet.
How much rest do I need at a given percentage of 1RM?
Above roughly 85% of your max, rest 3 to 5 minutes. Between 70 and 85%, rest 2 to 3 minutes. Below 70%, 60 to 120 seconds is usually enough. Higher intensities rely more on the ATP-PC system, which recovers slowly.