HOW 1RM IS CALCULATED
TABLE OF CONTENTS
- Introduction
- Our 1 Rep Max Calculator
- How Accurate Is This Calculation?
- Are There Other Formulas?
INTRODUCTION
While the most accurate way to determine a 1 Rep Max (1RM) is to actually physically do a 1 Rep Max attempt. This isn’t always possible such as when training around an injury, or productive since 1 rep max lifts aren’t regular part of most training programs.
However knowing your 1 rep maximum is a useful number for figuring what weights you should be using in your training program, and monitor progress toward your goals.
A 1 Rep Max calculator can be a useful substitute to physically attempting a 1 rep max lift as a quick and safe way to evaluate your training training progress over time, for updating your training program numbers as you get stronger, and tracking progress, or just ensuring your strength is where it needs to be for a competitive event.
OUR 1 REP MAX CALCULATOR
At 1-rep-max.com our 1 Rep Max Calculator is based on the Epley equation and is one of the more popular formulas used in the strength training world.
Employ Equation: 1RM = W(1+R/30)
Where:
W = Weight used
R = Number of Reps completed
1RM = Estimated 1 Rep Max
This equation assumes the weight used is a maximal effort between 1 – 30 reps.
HOW ACCURATE IS THIS CALCULATION?
Generally speaking the Epley method is within about 10% of a reasonably well trained weightlifters true 1RM when actually tested by lifting weights.
Novice lifters, lifters with health issues, or individuals recovering from injury may have real 1RM values significantly different than whats estimated via a these formula.
Adopting a structured training program, proper nutrition, and adequate recovery will both help your overall strength and the accuracy of an estimated 1RM.
For more factors that affect how closely your real world lifts compare to the calculated value check out our section about Why Is My 1RM Off?
ARE THERE OTHER FORMULAS?
Just like anything there are multiple different formulas out there for calculating your estimated 1 Rep Max that have been developed over the years. Some are targeted at specific sports or types of lifters.
In general the Epley and Brzycki formulas are most commonly used for generally well trained lifters. Fun fact these 2 actually return the same estimated 1RM max at 10 reps completed. They do very a little in estimated results in lower rep ranges (10 reps or less) with the Epley method returning a slightly higher estimated 1RM for calculations using rep values less than 10.
Here is a quick table of other 1RM formula estimations for those of you who may be interested.
Note: This table is from the fine folks over at Wikipedia
CONCLUSION
Generally speaking a 1RM calculator tool such as 1-Rep-Max.com are a safe and useful tool in estimating a lifters one rep max for training purposes.
A novice lifter, someone recovering from injury, or someone with health issues should take additional factors into consideration and proceed with caution, preferable with the oversight of a medical professional or trainer where appropriate.
Always use a safety spotter when attempting a 1 Rep Max and consult a doctor prior to starting any new training program.