Rep max comparison

Put in two sets with different weights and reps, such as a heavy triple and a set of six, to see which shows more strength.

Your details

Comparing 100 kg × 3 with 90 kg × 6

Set A

stronger by 1.9%

Set A estimated max110 kg
Set B estimated max108 kg
Reps in reserve countedset A 0, set B 0 (Zourdos 2016 scale: 0 means you could not do another)
Body weight changed?add your body weight on each day to compare strength for your size
FormulaEpley; on set A the two formulas differ by 3.7%

Both sets are turned into an estimated one rep max, so a heavy triple and a lighter set of eight can be compared fairly. Differences of a few percent are within the error of any formula.

The working

100 kg × 3 against 90 kg × 6

Set A: 100 × (1 + 3 ÷ 30) = 110 kg. Set B: 90 × (1 + 6 ÷ 30) = 108 kg. Set A shows about 1.9% more strength, which is close enough to call it a draw on a tired day.

If set B had 2 reps left in reserve, it counts as 8 reps to failure: 90 × (1 + 8 ÷ 30) = 114 kg, so set B was really the stronger one. With body weights of 80 kg and 78 kg, the maxes are 1.38 and 1.46 times body weight.

Why compare

Progress hides in rep ranges

Plans move between rep ranges, so a new rep best can be real progress even if the weight is lighter. Turning both into the same scale shows the trend.

Fair comparisons

Like for like

Same lift, same depth, same pause rules
Both sets taken close to failure
Sets of 12 reps or fewer
Ignore differences under about 3%

Read with care

What this cannot tell you

FatigueA set at the end of a session will always look weaker.
TechniqueChanging grip or stance changes the lift.
Small gapsGaps under a few percent are inside the formula's error.

Questions

Common questions

Is 3 reps at 100 kg better than 6 at 90 kg?

Slightly: about 110 kg against 108 kg estimated maxes.

Can I compare different lifts?

Not really; each lift has its own strength curve.

Which formula is used?

Epley by default, the most widely used for sets under about 10 reps; you can pick Brzycki or the average of both.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

Before you push on

New to exercise, or got a heart, lung or joint condition? Have a word with your GP or practice nurse first. Stop and get help if you feel chest pain, faintness or unusual breathlessness, and call 999 if it is severe.