A Better Way to Calculate Your 1RM

blog PL max It’s never been easy to accurately determine the maximum amount of weight you can lift for one rep.

You either expend a ton of time and energy as you lift, rest, add weight, lift, rest, add/reduce the weight, etc. – judging, missing, and guessing your way throughout the haphazard journey. This cycle continues until you find a true one-repetition maximum (1RM). The process, at best, will take 15-20 minutes per exercise and it can be exhausting – literally and figuratively.

Or you perform a submaximal set to failure and plug your numbers into an equation that may, or may not, have been clinically tested. Furthermore, many indirect methods (i.e., submaximal lifts) that calculate a 1RM require you to fail at a specific rep, say, rep 10 or the calculation won’t work.

Like I said, it’s not easy to figure out your 1RM.

But knowing your 1RM for the lifts you perform is beneficial, even if you’re not a competitive powerlifter, Olympic lifter or strongman competitor. There are two reasons why.

First off, many programs use percentages of the 1RM during the course of a training cycle to determine how much load you should put on the bar in each workout. Obviously, you’ll need to know your 1RM to get those training loads dialed in correctly.

The other reason it’s helpful to calculate your 1RM is because it’s not easy to always know if your maximum strength is increasing when you’re doing the most common type of exercise – submaximal resistance training. Last month you were using 60-pound dumbbells for 8 reps, this month you’re lifting 50-pound dumbbells for 12 reps. Did you get stronger?

It’s not easy to tell, right?

Before I outline the best indirect way I’ve found to determine your 1RM, I’ll say here that the purported risks of performing a true 1RM, from time to time, are often exaggerated. If you’re a person that has been training for a few years and adheres to strict lifting form, you should have little to worry about.

However, there are legit reasons why people don’t want to put in the time and effort to figure out their true 1RM. And many of you probably train people that don’t feel comfortable working up to the highest load and intensity possible.

If your clients feel that performing a 1RM test for the deadlift will cause them an injury, it probably will. No use in trying to convince them otherwise, just follow the clinically-tested calculation below and you’ll get the most accurate estimation I’ve found.

The 8-12 Formula Method

Step 1: Start with a load you would rate as a 5-6 on an intensity scale of 1-10 (10 being the highest) and perform 3-4 reps. Rest 1 minute.

Step 2: Add 10-15% to the load in step 1 and perform 3 reps. Rest 2 minutes.

Step 3: Choose a load that you feel will cause you to fail around 10 reps and perform as many reps as possible.

Of course, the likelihood of failing at exactly 10 reps is pretty low, even for experienced lifters who know their strength. And that’s the beauty of this formula: as long as you fail somewhere between 8-12 reps, the calculation will work. (Note: If you get less than 8 reps or more than 12 reps during the test, you’ll need to rest 3-5 minutes and try again with a lighter or heavier load.)

Here’s the formula:

(Load x Reps x 0.03) + Load = 1RM

Let’s say you tested the dumbbell overhead press with 60-pound dumbbells. You performed 9 reps, but failed to complete the 10th rep. The calculation will look like this:

(60 x 9 x 0.03) + 60 = 1RM
16.2 + 60 = 76.2

The calculation estimates that you could do one rep of the overhead press with 76 pound dumbbells (if they existed). But finding 76-pound dumbbells isn’t important: what’s important is being able to calculate your 1RM through various submaximal training cycles so you can determine if your maximum strength is increasing.

My advice: let math spare your joints.

Stay Focused,

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3 thoughts on “A Better Way to Calculate Your 1RM

  1. Great info Chad… would the formula work for any exercise, even isolation ones?

    CW: Of course.

  2. P.S. Does this formula work for those of us who use kg loading? Of not, please can you supply?


  3. CW: Yes, you’ll just have to convert pounds to kilograms. 2.2 pounds = 1kg. So if the load is 220 pounds that equals 100kg.

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