Explain it like I'm 12
One Rep Max Calculator averages Epley and Brzycki estimates and shows a training-max percentage for programming.
One Rep Max Calculator
One Rep Max Calculator estimates 1RM from lifted weight and reps using Epley and Brzycki checks.
Source references
- CDC Target Heart Rate and Estimated Maximum Heart Rate — public health target heart-rate reference
Formula
Epley = weight x (1 + reps / 30). Brzycki = weight x 36 / (37 - reps). Estimate = average of both formulas.
Worked example
100 for 5 reps gives about 116.7 by Epley and 112.5 by Brzycki, averaging about 114.6.
Professional note
For programming, a conservative training max is usually more useful than chasing the highest theoretical 1RM.
Regional and unit assumptions
General fitness estimate using the Karvonen heart-rate-reserve method.
Assumptions and limitations
- Best for lower-rep sets with good form.
- Technique, fatigue and exercise type affect real max strength.
- Do not test maximal lifts without appropriate safety.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Epley = weight x (1 + reps / 30). Brzycki = weight x 36 / (37 - reps). Estimate = average of both formulas.
Standard or basis
General fitness estimate using the Karvonen heart-rate-reserve method.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
For programming, a conservative training max is usually more useful than chasing the highest theoretical 1RM.
Related calculators
Questions
Is 220 minus age exact?
No. It is a rough population estimate and individual maximum heart rate can vary.
What is heart-rate reserve?
It is the gap between estimated maximum heart rate and resting heart rate, used to scale training intensity.
Calculation note
1RM formulas let lifters estimate strength from submaximal sets without always testing a true max.
One rep max needs assumptions beside the result
The calculator keeps the input values, formula trail and limitation note visible so the result can be checked later instead of treated as a magic number.
The printable record is part of the calculator
A useful result is one that can be compared with a statement, plan, workout log, timetable or worksheet after the page is closed.