1 Rep Max Calculator

Calculate the maximum weight you can lift / move in one single physical action. A great tool for body builders and those looking to improve their all round physical strength.

1 Rep Max Calculator
Weight lifted: kg or lbs
Number of repetitions:

Please provide a rating, it takes seconds and helps us to keep this resource free for all to use

[ 7 Votes ]

One Rep Max is the maximum weight an individual can lift in one single repetition. One Rep Max can be in any exercise, for example a dead lift, a bench press or arm curl. One Rep Max is most commonly associated with body building where an individual is looking to increase their overall strength or the strength of a specific muscle / muscle groups.

You do not need to physically complete the lift of weight in a single exercise to know your own personal One Rep Max, you can instead calculate your One Rep Max using the One Rep Max Calculator.

Why Do you need to know your One Rep Max?

The vast majority of those who workout regularly, whether in a home gym, at a public or private gym, with or without a personal trainer, rarely actually lift their One Rep Max. In fact, completing a One Rep Max can be difficult as the warm up and stretching to prepare can mean you don't quite have the right power to complete the exercise effectively and injury does occur more frequently when completely less reps with heavier weight. Those whose training program is all about go heavy and less reps have typically trained for several years and understand that correct technique, posture and a clear understanding of your bodies capability. More importantly, they have spotters they trust as performing one rep max exercises carries risk, requires incredible focus, belief, good breathing technique and TRUST. Did we mention trust? If things do go wrong when you attempt a One Rep Max, you want to make sure your buddy (or buddies, weight dependant) have your back.

So, if a One Rep Max lift takes so much dedication and can be risky why do it? Well, the answer is you don\t have to. Knowing your One Rep Max and lifting your One Rep Max are two very different things. Knowing your One Rep Max allows you to benchmark your progress. That could mean measuring your strength gain or it can be useful for ensuring you sustain a base level of strength when completing more cardio or stamina based exercise. This is what the majority of individuals who exercise and complete strength training require the One Rep Max Calculation for. It\s about benchmarking progress, a simple tool that allows you to measure and/or control your maximum strength for a particular muscle, muscle group or specific exercise.

So, in very simple terms, Your One Rep Max Calculation is your Benchmark for Strength Exercise Management. Now you know why knowing your One Rep Max is important, lets look at how to calculate your One Rep Max without actually lifting it.

How to calculate your One Rep Max

As with most things in life, their is a mathematical formula that allows the calculation of One Rep Max. Most people will use our One Rep Max Calculator but you may prefer to keep the One Rep Max formula in your head so you can roughly calculate your performance whilst in the gym, you can of course use our One Rep Max Calculator on your mobile but we think most people have enough equipment to juggle in the gym so here's a simple formula to keep in your head.

When completing resistance training, weight training, strength training, whatever flavour you wish to call it, most will focus on completing 10 repetitions of a single exercise, probably doing 3-4 sets of 10. 10 repetitions is a good balance, allowing for strength growth and definition. In case you don\'t know, higher repetition low weight gives greater muscle definition, lower repetition higher weight gives muscle growth and size (hence the term, bulking up). what most people don't know is that 10 repetitions of an exercise (assuming 10 is the final one you manage) is 75% of you one rep max or three quarters of your One Rep Max. with that simple knowledge, you can calculate your One Rep Max, let\s look at an example.

John wants to know his One Rep Max for arm curls. He completes 10 repetitions of arm curls using a 15kg bar with 10kg at either end, 45kgs in total. This is Johns 10 rep max.

10 Rep Max = 75% of One Rep Max

10 Rep Max = 3/4 of One Rep Max

10 Rep Max = 45kgs

45kgs divided by 3 = 15kgs

15kgs times four equals 60kgs

60kgs is Johns one Rep Max.

Repetition Percentages as a Ratio of One Rep Max

The following table provides an overview of how you can calculate your One Rep Max based on the number or repetitions you complete in comparison to the percentage of a One Rep Max.

Repetition Percentages of One Rep Max
Repetitions Percentage of 1RM
1 100%
2 97%
3 94%
4 92%
5 89%
6 86%
7 83%
8 81%
9 78%
10 75%
11 73%
12 71%
13 70%
14 68%
15 67%
16 65%
17 64%
18 63%
19 61%
20 60%
21 59%
22 58%
23 57%
24 56%
25 55%
26 54%
27 53%
28 52%
29 51%
30 50%

More Great Sports Calculators by iCalculator