RIR in Strength Training – What Does Reps in Reserve Mean?

If your training program says 2 RIR, what does that actually mean?

RIR stands for Reps in Reserve and describes how many additional repetitions you estimate you could have performed when you ended a set.

If you perform 10 repetitions and estimate that you could have completed a maximum of 12, you ended the set at approximately:

2 RIR

RIR therefore gives you a practical way to describe how close a set was to failure – without having to train all the way to failure every time.

What does RIR mean?

RIR is an estimate of how many good repetitions you had left.

A simple scale looks like this:

For example:

Bench press: 100 kg × 8 @ 2 RIR

This means:

You completed 8 reps with 100 kg and afterwards estimated that you could probably have completed approximately 2 additional reps.

Your maximum number of reps at that load would therefore have been around 10.

It does not mean that you definitely could have completed exactly two more.

RIR is an estimate.

What is failure?

To understand RIR, it helps to first understand failure.

In strength training, momentary muscular failure is typically used to describe the point at which you can no longer complete the concentric portion of a repetition despite maximal effort. Research uses different definitions of failure, however, which is one reason studies on the subject should be interpreted with some caution.

In practice, you can think of:

0 RIR ≈ failure

and:

3 RIR = approximately three possible reps away from failure.

The lower the RIR, the closer the set is to your current maximum capacity.

Why use RIR?

A traditional training program might say:

3 × 8 with 80 kg

But that does not necessarily tell you how difficult the work is for you.

For one person:

80 kg × 8

may be relatively easy.

For another person, the eighth repetition may be the final possible rep.

RIR therefore adds information about the effort behind the performance.

Instead, a program might say:

3 × 8–10 @ 2 RIR

Now the goal is not simply to reach a certain number of repetitions.

You should also finish the set with approximately two repetitions remaining.

This allows the load to adapt better to your current performance.

A practical example

Imagine you are training incline chest press with a target of:

8–10 reps @ 2 RIR

On a good day, you use 80 kg.

You perform:

80 kg × 10 @ 2 RIR

Next time, you are less well recovered.

With the same 80 kg, you perform:

80 kg × 8 @ 2 RIR

If your program only required 10 reps, you might be tempted to force out two more repetitions even though the set is already considerably harder than last time.

RIR allows you to keep the level of effort reasonably comparable, even when your day-to-day performance changes.

Do you need to train to failure to build muscle?

Not necessarily.

A systematic review and meta-analysis found no evidence that training all the way to momentary muscular failure was superior to non-failure training for muscle growth.

A newer meta-regression from 2024 provides a more nuanced picture: muscle growth generally appears to increase as sets are terminated closer to failure. For strength, however, the analysis did not find the same clear relationship between estimated RIR and strength gains.

That does not mean:

The harder the better, and 0 RIR is always optimal.

It means that proximity to failure is a relevant training variable, particularly when the goal is muscle growth.

You can therefore train hard and close to failure without necessarily taking every set all the way to failure.

Is 1–3 RIR the perfect range?

You will often see recommendations such as 1–3 RIR.

This can be a practical range for many working sets, but RIR should not be treated as a universal rule.

How close you want to train to failure depends on factors including:

• the exercise
• the load
• your goal
• the number of sets
• training experience
• recovery
• how much fatigue the exercise creates

A set of lateral raises at 0 RIR and a heavy set of squats at 0 RIR, for example, do not necessarily have the same practical consequences for the rest of your training.

RIR is therefore a tool for managing training, not a requirement that every exercise be performed at exactly the same value.

How accurately can you estimate RIR?

Not perfectly.

When you say:

“That was 2 RIR”

it is still a subjective estimate.

A systematic review of 26 studies found that RIR estimates generally become more accurate when a set is terminated closer to failure and at higher relative loads. Estimation becomes more difficult further away from failure and at lighter loads involving many repetitions.

That makes intuitive sense.

It is easier to distinguish between:

“I could maybe do one more”

and:

“I could not do another rep”

than between:

“I had maybe six, eight or ten reps left.”

Very high RIR values therefore often provide less precise information.

Do you get better at estimating RIR with experience?

It is more nuanced than simply saying that experienced lifters are accurate.

A recent study of the back squat, for example, found no significant difference between novice and more experienced participants when estimating 1 and 3 RIR. The researchers suggested that experience with high-effort training may matter more than simply the number of months or years someone has been strength training.

The practical point is:

You should not expect your RIR estimates to be perfect from the beginning.

But you can become more familiar with your own level of effort.

One simple approach is to occasionally – on appropriate exercises – compare your estimate with what you can actually perform.

If you stop at what you believe is 2 RIR but consistently could have completed five additional reps, you are underestimating your reserve.

If you believe you had 2 RIR but could only complete one more rep, the set was closer to failure than you estimated.

This does not mean you need to test failure all the time.

The purpose is to calibrate your perception.

RIR and progressive overload

RIR becomes particularly useful when combined with progression.

Imagine:

Week 1:
100 kg × 8 @ 0 RIR

Week 4:
100 kg × 8 @ 2 RIR

If you only record weight and repetitions, the performances appear identical.

But they are not necessarily identical.

In week 4, you probably have greater capacity at the same load.

RIR can therefore help reveal progress that weight and reps alone do not show.

This connects directly with progressive overload: the goal is not necessarily to increase the weight in every workout, but for your capacity to develop over time.

→ Read FRAMIR’s guide to progressive overload

How do you use RIR for progression?

Imagine a program:

3 × 8–10 @ 2 RIR

You start with 80 kg.

Workout 1

80 kg × 8 @ 2 RIR

Workout 2

80 kg × 9 @ 2 RIR

Workout 3

80 kg × 10 @ 2 RIR

Now you can increase the load:

Workout 4

82.5 kg × 8 @ 2 RIR

This is a practical combination of:

rep range + RIR + progressive overload

You do not increase the weight simply because another week has passed.

You increase it when your performance indicates that you are ready.

RIR and RPE – what is the difference?

RIR and RPE describe related concepts.

RIR asks:

How many reps did I have left?

RPE describes the level of perceived exertion.

In strength training, they are often related approximately like this:

This is a practical translation – not an exact physical measurement.

We will cover the distinction in more detail in FRAMIR’s guide to RPE.

RIR is a tool – not an exact answer

It is tempting to make training more precise than it really is.

A set does not need to be exactly:

2.000 RIR

to be productive.

If your estimate is reasonably close to reality and you use it consistently, RIR can help you:

• manage training intensity
• avoid unnecessary failure
• adapt training to your daily readiness
• compare effort between workouts
• manage progression more systematically

But RIR should be used together with other information:

weight + reps + sets + technique + progress over time.

The combination provides a better picture of your training than any single number.

Track your training and 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 see what you did last time and make better decisions about your next workout.

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In short

RIR means Reps in Reserve and describes how many repetitions you estimate you had left when a set ended.

• 0 RIR = no reps left
• 1 RIR = approximately one rep left
• 2 RIR = approximately two reps left
• 3 RIR = approximately three reps left

RIR is an estimate – not a perfect measurement.

It generally becomes easier to estimate closer to failure, and you do not need to take every set all the way to failure to make progress.

Combined with weight, reps and training history, RIR can make it easier to manage both effort and progression.