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5 Ways to measure 1RM strength in the gym

For gym-goers looking to track strength gains, knowing the absolute maximum weight you could lift for one repetition is a powerful piece of knowledge. Whether this is to simply keep track of progress over time, provide competition and motivation in your training or as a cornerstone of your programming and periodisation structure through percentage based training, the ability to accurately and regularly measure your one rep max (1RM) is essential.

There are many well-researched and valid methods to find your one rep max on compound barbell exercises like the bench press, overhead press, back squat, front squat and deadlift. In this article we will unpack five of the best approaches to measuring 1RM strength levels on your favourite exercises. (spoiler alert, #5 is my personal favourite! 😉)

TLDR: The most time-efficient and safest approach to estimating your 1RM is to use a barbell velocity tracking app/device and create your own velocity based training (VBT) chart - known as a load velocity profile to accurately estimate your maximum strength levels. All without the risk and fatigue accumulation of max effort testing efforts.
To create your own load velocity profile download the Metric app (on iOS) and then use the free load velocity profile calculator on this website.

1. Direct 1RM testing

The most accurate way to measure your 1RM is to test it directly, by loading up the bar and performing a 1RM!

Pros and cons of 1RM strength testing

The benefits of knowing your exact 1RM are obvious in that precision and practice of pushing your limits can be incredibly useful. However, performing this test with high frequency can be quite a distraction from your training routine, as it takes a lot of time, and recovery.

I have written at length about the technical. logistical, safety, and performance costs of training to failure in another article, but it bears repeating: 1RM testing should be taken seriously and treated with respect. Any maximum effort attempt has inherent risks if a lifter does not approach them with focus and in a safe environment.

Pushing yourself to true maximal efforts with heavy weights requires skill, sound technique and focus. While injuries are rare in sports like powerlifting (a sport built around the 1RM!) going into a 1RM ill-prepared is a bad idea. Always have an experienced spotter watch your lifts and ensure you maintain solid technique. Don't let your ego push you into unsafe territory.

The test itself is time consuming to properly warmup and attempt multiple singles, while the strain and stress of heavy singles on the nervous system can be a major disruption to your regular training schedule.

How do you complete a 1RM test?

A one-rep max (1RM) test involves an incremental warmup of progressively heavier sets completing reps until you cannot complete a single repetition. The test ends when you fail to complete a rep (assisted by a spotter, fail to lock out the weight or compromise your technique too much). Usually three genuine 1RM attempts are allowed following a series of graded warmup sets.

For a detailed breakdown of 1RM testing protocols check out this blog post →

2. Estimate 1RM from any set to failure

A slightly more efficient way to estimate your 1RM, is to perform a set to failure between 2-6 repetitions and extrapolate out from this to predict your 1RM.

For example by doing a 3RM, 5RM, 6RM etc you can use one of a number of validated formula to to convert the load lifted here into a predicted weight for your 1RM.

A conversion chart for calculating a 1RM from a set to failure with 1-10 repetitions.
One example of a conversion chart for calculating a 1RM from a set to failure with 1-10 repetitions.

While not as precise as a true 1RM, this method reduces injury risk and saves a bunch of time. Here is how.

  • Less time cost. Instead of needing three attempts at the maximum effort set (and the associated rest), an RM attempt requires just one all-out set. You just take that one weight for as many reps as you can before failure
  • Margin for error. Because the weight is lighter in both absolute and relative terms there is less chance of a serious miscalculation, you know you are going to get two reps on the selected weight, its just a question of whether you can maybe get 3, or 4 in order to push the estimated 1RM score up!

Testing with lighter weights still requires maximal effort sets so it still leads to fatigue, and probably requires some level of deload in the days prior, but it is overall more efficient.

Reps to failure testing protocols

Once you have completed your rep maximum set (between 2-6 reps), you will need to convert this score into a 1RM. To do this you simply plug in the load and rep values from your test into one of the formula listed below and it will provide back a 1RM prediction.

Best 1RM formula

There are a seven well number of sophisticated methods for estimating 1RM from this data, based on different scientific findings, these equations are:

  • Brzycki: load × (36 / (37 - reps))
  • Epley: load × (1 + 0.0333 × reps)
  • Lander: (100 × load) / (101.3 - 2.67123 × reps)
  • Lombardi: (load × reps)0.1
  • Mayhew et al.: (100 × load) / (52.2 + (41.9 × e-0.055 × reps))
  • O’Conner et al.: load × (1 + 0.025 × reps)
  • Wathan: (100 × load) / (48.8 + (53.8 × e-0.075 × reps))

Links to the references can be found below (Wood, 2009 was where I found all 7 1RM equations).

I have combined all of these 1RM equations into a free online calculator, it provides the 1RM estimate based on all seven formula independently along with an average 1RM. I tend to use the averaged result for all my lifts to maintain consistency!

You can try the 1RM rep max calculator on this page →

3. RPE 1RM conversion

Rate of perceived exertion (RPE) is a way for lifters to subjectively rate how close a set is the the point of failure with 10 RPE being a maximum effort set.*

*Some lifters and coaches prefer to use an RIR (reps in reserve) scale where 0 is a maximum effort set, and 4 representing 4 reps in reserve (4 reps before the point of failure).

Skilled lifters - especially powerlifters - with plenty of training experience can develop uncanny accuracy when using RPE in their training, and as such formula have been created that that are able to estimate 1RM without having to perform a maximum effort set. Simply take the weight lifted, reps performed, and RPE for that set to estimate daily 1RM capabilities and generate a personalized RPE load chart.

A conversion chart for comparing % of 1RM and RPE for calculating strength
An example RPE - load - rep scale chart. You can create your own with the VBTcoach RPE-1RM calculator

This table shows the relationship between RPE, reps completed and the % of 1RM that the set was performed at, there are even relationships between RPE and bar speed, specifically last rep velocity. You can use the free VBTcoach RPE - 1RM calculator to assess your 1RM from any set during your sessions.

Create your own RPE scale and estimate 1RM with this free calculator →

Limitations of RPE in strength training

RPE has drawbacks for all levels. Biggest of which is that lifters may over or underestimate RPE, skewing their 1RM estimation — often without even realizing it.

As a subjective measurement of exertion, RPE (and RIR) is prone to bias. Ego, mood, motivation levels, time of day, music, hydration, and any number of other factors can influence and nudge how a lifter might rate their proximity to failure on a given set.

For experienced lifters who are familiar with lifting heavy and with a good self-awareness of their limitations, this bias is better controlled and RPE/RIR is accurate enough to accurately estimate 1RM and proximity to failure from submaximal training

On the other end of the spectrum, most beginners lack the experience to accurately rate RPE across various weights and fatigue levels. More objective strength testing methods are better suited to novice and early intermediate lifters (see the velocity tracking methods below).

For these reasons, more objective testing like velocity tracking can complement and support RPE as a way to monitor strength and progress without limitations of subjective intensity ratings.

4. Isometric strength tests

A very alternative approach to estimating 1RM is to not bother with the 1RM, something that I think might be growing in popularity with the rise of velocity based training (VBT) thanks to bar speed tracking apps. VBT is one approach (more on this in #5) but it’s worth also mentioning the use of force plates and isometric strength tests.

Isometric strength tests measure force production in a specific and fixed joint-angle with force plates or similar technology. To do an isometrics strength test such as an IMTP (Isometric mid-thigh pull) the athlete gets into the testing position and pulls on the bar as hard as they can for 3-5 seconds.

The big advantage of isometric strength testing is it is safe and really efficient for tracking strength changes on a regular basis, without having to perform a taxing max effort set or go through a lengthy 1RM testing protocol.

Isometrics do have limitations though as they still do not assess dynamic strength capabilities on the exercises used in training, and they do require expensive hardware to conduct the tests. The fixed testing position and join angle may have limited transfer and not fully reflect strength capabilities on compound lifts.

Still, an interesting area with growing data and interest, especially as an injury prediction tool in elite sport!

5. Velocity based training to estimate 1RM strength

The ultimate method to estimate your 1RM, without actually doing a 1RM is to utilise velocity based training (VBT) and create a load velocity profile.

Using bar speed tracking technology like the free Metric VBT app can objectively and accurately measure the speed of all your lifts and use this information to reliably assess strength levels on your barbell lifts.

By collecting bar speed data during a normal training session with a velocity tracking app like Metric VBT it is possible to create a load velocity profile and accurately estimate your 1RM performance on any lifts — all without doing any extra or different sets from your regular workout.

The ability to do this relies on a key velocity based training concepts: The load velocity profile and the minimum velocity threshold.⁠⁠ ⁠

Load-Velocity profile

The relationship between weight lifted and the speed at which you can move that weight is known as a load-velocity profile. For the big strength lifts (squat, bench, deadlift) this profile is predictable, consistent and remarkably linear.

Calcuate your strength 1RM with velocity based training and the load velocity profile
Estimating 1RM from the load velocity profile with bar speed data

Minimum velocity threshold

The Minimum velocity threshold (MVT) is the speed at which you move the barbell on a 1RM. If the bar were any heavier (beyond 1RM) the lifter would not be strong enough to accelerate the bar through the sticking point and they would fail the repetition.

Measured in mean velocity (m/s) this MVT value is stable and (somewhat) consistent, allowing us to accurately extrapolate from a lifters load velocity profile and find the weight at which their 1RM is most likely to be — all without having to do any sets even remotely close to failure.

Calculating 1RM with bar speed data

I have written in detail about how velocity based training can help us accurately estimate 1RM values previously, but in a nutshell:

  • Perform 3-5 sets across a range of weights
  • Record velocity for each set with Metric VBT
  • Log the fastest rep from each set along with its weight into the calculator
  • Get back a chart for your profile along with an estimated 1RM score.

You can use the load velocity profile tool here for free →

Benefits of the velocity based training method

With this approach to 1RM estimation you can effectively “test” your 1RM every single session, simply using the mean velocities collected across your warm up sets as the data points to generate a load velocity profile, as long as you stick with a consistent MVT for a given exercise, you can safely know that if the 1RM estimate is going up then you are getting stronger.

I think this is so valuable, I have written an entire blog all about how useful velocity based training is for 1RM testing. And if you are looking for a way to measure your velocity in the gym, check out my app Metric VBT, its free to use and doesn’t require any expensive devices, just the iPhone in your pocket!

Learn more about Metric VBT and download the app at this link →

I have a heap of 1RM calculators, that take advantage of a range of different approaches and protocols for estimating and measuring your one rep max.

You can try them all for free at this link →

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References and resources

  • Reynolds 2006: Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry
  • Wood, 2009: Accuracy of Seven Equations for Predicting 1-RM Performance of Apparently Healthy, Sedentary Older Adults
  • Picerno, 2016: 1RM prediction: a novel methodology based on the force–velocity and load–velocity relationships
  • Weakley, 2021: Velocity-Based Training: From Theory to Application
  • Thompson, 2021: A Novel Approach to 1RM Prediction Using the Load-Velocity Profile: A Comparison of Models
  • Pérez-Castilla, 2021: Validity of Different Velocity-Based Methods and Repetitions-to-Failure Equations for Predicting the 1 Repetition Maximum During 2 Upper-Body Pulling Exercises
  • Zourdos, 2016: Novel Resistance Training–Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve
  • James, 2023: The Relationship Between Isometric and Dynamic Strength Following Resistance Training: A Systematic Review, Meta-Analysis, and Level of Agreement

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