RIR vs. RPE – What’s the Difference?

RIR and RPE are both used to describe how difficult a set is and how close you are to failure.

They simply approach the question from different directions.

RIR asks:

How many reps did I have left?

RPE asks:

How hard was the set?

In the RIR-based RPE scale, the two are approximately related like this:

This means:

100 kg × 8 @ 2 RIR

and:

100 kg × 8 @ RPE 8

describe approximately the same proximity to failure in practice.

But RIR and RPE are still subjective estimates, not precise physical measurements.

What is RIR?

RIR stands for Reps in Reserve.

You estimate how many additional repetitions you could have completed when you ended the set.

If you perform:

80 kg × 10 @ 2 RIR

you are estimating that you probably could have completed around 12 repetitions in total.

RIR therefore asks a very direct question:

How many reps did I have left?

→ Read the complete guide to RIR

What is RPE?

RPE stands for Rating of Perceived Exertion and describes perceived effort.

In the RIR-based RPE model commonly used in strength training:

RPE 10 corresponds approximately to no reps remaining.

RPE 9 corresponds approximately to one rep remaining.

RPE 8 corresponds approximately to two reps remaining.

So if you perform:

80 kg × 10 @ RPE 8

you are describing the set as hard, but with approximately two possible repetitions remaining.

→ Read the complete guide to RPE

RIR vs. RPE – the short version

The simplest way to distinguish them is:

Notice that the scales move in opposite directions:

Lower RIR means harder work.

Higher RPE means harder work.

Which system is easier to use?

That depends on how you naturally think about a set.

RIR may be easier if you think in reps

After the set, ask yourself:

Could I have completed one, two or three more?

If the answer is approximately two, you record:

2 RIR

It is simple and direct.

RPE may be easier for autoregulation

If your program says:

3 × 5 @ RPE 8

you have a target for the difficulty of the set.

On a strong day, reaching that target may require more weight.

On a poorer day, it may require less.

RPE can therefore be useful in programs where load is adjusted according to daily performance.

Is RPE 8 always exactly 2 RIR?

No.

The relationship:

RPE 8 ≈ 2 RIR

is a practical model.

It is not an exact biological conversion.

Both RPE and RIR depend on your own judgement, and research shows that the ability to estimate repetitions in reserve varies. Estimates generally become more accurate when sets are terminated closer to failure.

You should therefore not treat:

RPE 8 = exactly 2.000 RIR

as a mathematical truth.

The goal is to obtain a useful estimate of effort.

Should you use both RIR and RPE?

Not necessarily.

If you already understand and use RIR consistently, you do not also need to record RPE for every set.

And if your program is built around RPE, you do not necessarily need a separate RIR value.

What matters most is that you:

• understand the scale
• use it reasonably consistently
• combine it with weight and reps
• follow your progress over time

RIR and RPE are tools.

They are not the goal of training.

A practical example

Imagine you are training incline chest press.

Workout 1

80 kg × 8 @ 2 RIR

This corresponds approximately to:

80 kg × 8 @ RPE 8

A few weeks later

80 kg × 10 @ 2 RIR

or approximately:

80 kg × 10 @ RPE 8

You are now performing more reps at approximately the same relative effort.

That is a clear sign of progress.

The next step might be:

82.5 kg × 8 @ 2 RIR

This is where RIR and RPE become particularly useful together with progressive overload.

→ Read the guide to progressive overload

RIR and RPE do not tell the whole story

A single RIR or RPE value cannot tell you everything about a set.

It should be considered together with:

• weight
• reps
• number of sets
• technique
• exercise
• training history
• progress over time

For example:

100 kg × 8 @ RPE 8

may represent a better performance than:

100 kg × 8 @ RPE 9

because you achieved the same weight and repetitions with more capacity remaining.

But that information becomes most useful when you can compare it with your previous training.

RIR, RPE and 1RM

RIR and RPE primarily describe effort within a set.

1RM describes something different: your maximal or estimated strength for one repetition.

They can therefore complement each other.

For example, you can track:

weight + reps + RIR/RPE + estimated 1RM

to gain several perspectives on your progress.

FRAMIR has a free 1RM Calculator if you want to estimate your maximum from a normal working set.

→ Calculate your estimated 1RM

Track your progress with FRAMIR

FRAMIR is built to make your training and progress visible.

You can track:

• exercises
• sets
• weight
• reps
• programs
• workout history
• progression
• estimated 1RM

So you can compare your workouts and see whether your capacity is actually improving.

Start FRAMIR in your browser

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In short

RIR and RPE both describe training effort, but from different directions.

RIR: How many reps did I have left?

RPE: How hard was the set?

In the RIR-based RPE model, approximately:

• 0 RIR ≈ RPE 10
• 1 RIR ≈ RPE 9
• 2 RIR ≈ RPE 8
• 3 RIR ≈ RPE 7

You do not need to use both systems.

Choose the system that makes the most sense to you, use it consistently, and combine it with your training history.