Straddly logostraddly
Get on Google Play
Free tool

1RM calculator

Enter a set you did recently. Get your estimated one rep max and the loads for every training percentage.

Unit
Exercise type
lb
Estimated 1RM260 lbAverage of 3 formulas
Epley
263 lb
Brzycki
253 lb
Lombardi
264 lb
Your training loads
% of 1RMLoadTypical reps
100%260 lb1
95%247 lb2
90%234 lb3-4
85%221 lb5-6
80%208 lb7-8
75%195 lb9-10
70%182 lb11-12
65%169 lb13-15
60%156 lb16-20
55%143 lb20-25
50%130 lb25+

How the 1RM calculator works

Your one rep max (1RM) is the heaviest load you can lift once with good form. Testing it is tiring and a bit risky, so most lifters estimate it from a harder set of 2 to 10 reps.

The calculator runs three well-known formulas on your set and shows their average. The formulas stay close under 6 reps and drift apart as reps go up, which is why the estimate gets less reliable above 10 reps.

For a deeper look at when to trust an estimate, read how to estimate your 1RM without testing it.

Put this calculator on your site

Free for coaches, gyms and bloggers. Paste this snippet where you want it: it resizes itself, works on mobile and stays up to date.

<div data-straddly-tool="one-rep-max" data-lang="en">
  <a href="https://straddly.app/tools/1rm-calculator">1RM calculator by Straddly</a>
</div>
<script async src="https://straddly.app/embed.js"></script>

1RM formulas and percentage chart

These are the three equations used above, followed by the typical number of reps people manage at each share of their max.

1RM formulas and percentage chart

FormulaEquationTends to
Epley1RM = w × (1 + r / 30)Sit in the middle, matches Brzycki at 10 reps
Brzycki1RM = w × 36 / (37 - r)Read lowest at low reps, climb fastest past 10
Lombardi1RM = w × r^0.10Read highest at low reps, lowest at high reps
w = weight lifted, r = reps completed.

Typical reps at each percentage of 1RM

% of 1RMTypical reps
100%1
95%2
90%3-4
85%5-6
80%7-8
75%9-10
70%11-12
65%13-15
60%16-20
55%20-25
50%25+

Weighted pull-ups, dips and other bodyweight lifts

On a weighted pull-up you lift your whole body plus the plate, not just the plate. Switch to bodyweight mode, enter your bodyweight and the added weight, and the calculator works on the total load.

The result shows your estimated total 1RM and the extra weight you could hang for a single rep. In the chart, a negative added weight means you would need assistance, like a band, to hit that percentage for reps.

How to use your 1RM in training

Most programs prescribe work as a percentage of 1RM. Strength blocks live around 80 to 90%, hypertrophy work around 65 to 80%, and technique or speed work below that.

  • Pick a training max of about 90% of your estimate if your program asks for one.
  • Re-estimate every few weeks from a hard set instead of testing a true single.
  • Use the same lift and depth or range of motion each time, or the numbers will not compare.

Straddly does it after every set

In Straddly you just log your sets. The app estimates your 1RM for each set, including bodyweight exercises where your bodyweight counts in the load, and flags a personal record the moment you beat your best.

Frequently asked questions

Which 1RM formula is the most accurate?

None is best for everyone. Under 6 reps the three stay within about 5% of each other. Brzycki reads lowest at low reps and climbs fastest past 10, Lombardi does the opposite. Averaging them smooths out their bias, which is why the calculator shows the average first.

How many reps should I use to estimate my 1RM?

A set of 3 to 6 hard reps gives the most reliable estimate. Above 10 reps the result depends more on your endurance than your strength, so treat it as a rough guide.

How do I calculate my 1RM for weighted pull-ups or dips?

Add your bodyweight to the plate you used, since you lift both. For example, 80 kg bodyweight plus 20 kg for 5 reps is a 100 kg set, about a 115 kg total 1RM, so roughly 35 kg added for a single.

Is an estimated 1RM as good as a real max test?

For programming, yes. An estimate from a hard set is usually within a few percent of a tested max, and you avoid the fatigue and risk of a true single. Powerlifters still test before a meet to practice the heavy single.

How often should I update my 1RM?

Every 4 to 8 weeks is enough for most people, or whenever your working sets clearly feel easier. Straddly updates it for you each time you log a set.

More free tools

Free tools for lifters and calisthenics athletesTraining blogStraddly workout tracker