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How to Find Your One-Rep Max

Strength is your ability to generate force and is best expressed by the amount of weight you can lift once. Strength is usually defined as your one-repetition max, or 1RM for short. Weightlifters and powerlifters live and die by their 1RM but knowing it can be helpful for other exercisers, too, especially if you are training for strength.

You can use your 1RM to measure performance improvements. If you are getting stronger, your training plan is working well, and you should stick with it. Seeing your 1RM increase is very motivating.

Many popular resistance training programs use 1RM to prescribe what weights to lift. For example, you may be instructed to perform ten reps using 70% of your 1RM. Obviously, to do this, you’ll need to know your 1RM in the first place.

Finally, it can be fun to discover just how strong you are – even if you never have any intention of entering a powerlifting or weightlifting competition. Knowing your 1RM also means that you can answer that eternal strength training question; how much can you bench press?

In this article, we reveal how to find your one-rep max.

How to Find Your One-Rep Max

Testing Your 1RM Max?

Power lifter one rep max

If you want to discover your actual 1RM, ramping up probably the best way to do it.

However, it is not without risks. Lifting heavy weights puts a lot of stress on your muscles and joints and will magnify any technique faults, such as rounding your lower back during deadlifts.

Only test exercises that you are very familiar with and can do with good form.

Also, to confirm you have hit your 1RM, your next attempt needs to be a failure. Why? Because you’ll never know if you could have lifted more unless you try. Needless to say, for most exercises, that means having spotters on hand. A failed squat or bench press can cause serious injuries.

To ramp up to your 1RM, do a single rep with a relatively light weight – around 50% of your anticipated 1RM. Rest a moment, increase the weight by 7-10%, and lift again. Keep adding weight rep by rep until you max out. Try to hit your 1RM in 5-8 attempts.

Rest 2-3 minutes between early attempts and 3-5 minutes as you get closer to your maximum. Remember to go one step further and try the next weight up from your last successful lift. If you don’t, you could end up underestimating your 1RM.

Predicting your 1RM with The Epley Formula

If maxing out on single reps is not for you, maybe because you don’t have access to reliable spotters, you can predict your 1RM using something called the Epley formula.

Using this formula, you perform your chosen exercise to failure and then use the number of reps to estimate how much weight you could lift for one rep. You can use this formula to establish 1RM for any exercise, and most online 1RM calculators use the Epley formula.

In theory, you can use the Epley formula with any number of reps. However, the lower the rep count, the more accurate your prediction will be. Ideally, try and reach failure between 4-8 reps.

The Epley formula looks like this:

Weight x reps x 0.0333 + weight = e1RM (estimated one-repetition maximum)

For example, if you did five reps with 90 kilos and were unable to complete a sixth:

90 x 5 x 0.0333 = 14.985 + 90 = 104.985, which we’ll round up to 105 kg – the nearest available weight plate denomination.

You can also work out your 1RM using a coefficient chart like the one below. Simply multiply the weight lifted by the coefficient that matches the number of reps performed:

Reps performed Lower body Upper body
1 1.00 1.00
2 1.0475 1.035
3 1.13 1.08
4 1.1575 1.115
5 1.2 1.15
6 1.242 1.18
7 1.284 1.22
8 1.326 1.255
9 1.368 1.29
10 1.41 1.325

For example, if you did seven reps with 65kg on a lower body exercise, your estimated 1RM would be 79.3kg (65 x 1.22).

How Often Should You Attempt A One-Rep Max?

Man aout to bench press

1RM testing is very demanding. Each attempt is over in just a few seconds but lifting the heaviest weight possible takes a toll on your nervous system.

Pushing yourself to the limit also takes a lot of your body, and the more often you test your 1RM, the more likely you are to get injured.

As such, you should avoid doing 1RM testing too often. Once every couple of months is plenty. This will also give your workout plan time to work its magic. Test too often, and there may not be any progress to measure.

You could do a predicated 1RM test a little more often, as doing so involves working with submaximal weights. However, as before, if you test too often, there won’t be much progress to see.

Finally, ask yourself if you NEED to know your 1RM. If you don’t, it’s probably not worth the risk.

What Percentage of Your 1RM Is A 10-Rep Max?

Once you know your 1RM, you can estimate how much weight you can lift for any number of repetitions. For example, your 10-rep max equates to roughly 75% of your 1RM. Where some workouts are prescribed using a percentage of your 1RM, others tell you to use your five, eight, or ten rep max.

Use this chart to make sure you are using the right training load for your workout.

1RM% 70% 75% 77% 80% 83% 85% 87% 90% 93% 95% 100%
Reps 12 10 9 8 7 6 5 4 3 2 1

Bottom Line

Not all exercisers need to know their 1RM. If you aren’t training for strength, it really serves no purpose. Just train to within a rep or two of failure and using the appropriate rep range, and you’ll get the results you want without knowing how the weight compares to your one-rep max.

If you want to get stronger and measure your progress, knowing your 1RM may be helpful. And, if you are a powerlifter or an Olympic weightlifter, knowing how much weight you can lift for one rep is all but essential.

There are several ways to establish your 1RM. For most people, the Epley formula is the safest and most convenient way. Just rep out using a moderately heavy weight that forces you to fail between 4-8. Make a note of the load and number of reps performed, and then plug your numbers into Epley’s equation.

Alternatively, you can use a coefficient chart, like the one in this article. Multiply the weight by the coefficient corresponding to the number of reps to estimate your 1RM. The math is easier than for the Epley formula, and there are coefficients for upper body and lower body exercises.

Alternatively, you can use an online 1RM calculator or app; there are plenty to choose from.

Patrick Dale is an ex-British Royal Marine and owner and lecturer for a fitness qualifications company. In addition to training prospective personal trainers, Patrick has also authored three fitness and exercise books, dozens of e-books, thousands of articles, and several fitness videos.

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