What is RiTiS? Comparing sets of different reps and RPEs

Is 5 reps at RPE 8 harder than 3 reps at RPE 7? What about 8 at RPE 9? Reps and RPE both contribute to how hard you are working, but they make sets hard to compare. RiTiS is Auriga's way of squashing both into one number, so a set of 8 and a heavy single can be compared.

RiTiS is short for "Reps In Tank If Single". It answers one question: if you'd done this weight for a single instead, how many reps would you have had left in the tank?

Take your reps, subtract one, then add your reps in reserve (RIR, which is 10 minus your RPE):

RiTiS = reps − 1 + RIR = reps + 9 − RPE

The "minus one" is there because a single has no extra reps to count, so a single at RPE 10 gives a RiTiS of zero. A true max single is RiTiS 0, and the higher the RiTiS, the further the set was from your max. Some examples:

A single at 6 should be the same weight as a double at seven, a triple at 8, and a four at nine. The RPE changes, but the RiTiS is the same. So RiTiS is a useful tool to predict what weight you should do in a set.

If you plot the weight you used against RiTiS for lots of sets, they sit along a curve, and the curve says something really important about your lifting. Where it meets RiTiS 0 is your estimated one rep max. How steeply it drops tells you how much your weight falls for every extra RiTiS: your fatigue scaling.

That's the Weight vs. RiTiS chart on The Hierophant. Colour shows the reps, how solid a point is shows its RiTiS (solid points were closest to failure), and the shape shows which block it came from.

Say your e1RM was 200kg and your weight dropped about 3.3% for every extra RiTiS. The curve would suggest about 187kg at RiTiS 2 (a single at RPE 8), about 175kg at RiTiS 4 (3 @ RPE 8), and about 164kg at RiTiS 6 (5 @ RPE 8).

(Illustrative numbers, not a real athlete. 3.3% is based on the Epley charts.)

Every lifter scales at a different rate as the reps climb. The chart uses your own logged sets to find your fatigue scaling.

Which is why it needs a few sets: at least three sets rated RPE 4 or higher, with at least two different RiTiS values. Sets below RPE 4 are ignored by default, but there is a toggle on the page that lets you include more.

If you haven't logged enough yet, Auriga uses a fixed 3.3% per RiTiS instead, which lines up with the per-rep change in the Epley formula (weight × (1 + reps / 30)), and says so on the chart. It's a fallback to get you started, not a replacement for your own numbers.

These charts are only as honest and accurate as the RPE going into them. If you rate everything RPE 8 whether it was or not, the number will mean little. See our RPE article for how to build that judgement.

Happy lifting!