Reps in Reserve help you understand how hard you’re actually training. Because just because your program says 8 reps doesn’t mean those 8 reps feel the same for everyone.
That’s where RIR (Reps in Reserve) comes in: How many clean reps could you still have performed after finishing your set?
We’ll show you how to estimate RIR, how many reps you should leave in the tank and how to use RIR in your training.
What Does RIR Mean in Training?
RIR stands for Reps in Reserve and describes how many technically clean repetitions you could probably still have performed at the end of a set.
The lower your RIR, the closer you were to muscular failure.
| RIR | Meaning |
|---|---|
| 4 RIR | You could have performed about 4 more reps |
| 3 RIR | You could have performed about 3 more reps |
| 2 RIR | You could have performed about 2 more reps |
| 1 RIR | You could have performed about 1 more rep |
| 0 RIR | You couldn’t have performed another clean rep |
Let’s say your program calls for 3 × 8 Back Squats @ 2 RIR. You should choose a weight that allows you to complete eight reps while still having around two technically clean reps left in the tank.
That might mean 80 kg on one day and only 75 kg on another. Your performance doesn’t just depend on what’s written in your training plan. Sleep, stress, previous sessions and your overall recovery can all affect how much you’re capable of on a given day.
That’s one of the main advantages of RIR training: The load isn’t based solely on a fixed weight, but also on how challenging that weight actually is for you at that moment.
Why Are Reps in Reserve Useful?
Imagine two athletes both perform eight Back Squats at 80 kg. Athlete A could have done another five reps. Athlete B could probably have managed only one more.
On paper, they completed exactly the same set. But the actual training stimulus wasn’t the same.
Reps in Reserve help account for that difference. Instead of looking only at weight, reps and sets, RIR adds another important factor: your individual level of effort.
RIR vs. RPE: What’s the Difference?
If you already use RPE (Rate of Perceived Exertion) in your training, the concept will probably sound familiar. Both systems are used to estimate the subjective intensity of a set, but they approach it from different directions.
With RIR, you ask: How many more reps could I have done?
With RPE, you rate how hard the set felt, usually on a scale from 1 to 10.
For hard strength sets, the two systems can be roughly compared like this – the same link the RIR-based RPE scale by Zourdos et al. (2016) is built on, which many training programs use today:
| RIR | RPE | Estimate |
|---|---|---|
| 4 RIR | RPE 6 | Around 4 reps remaining |
| 3 RIR | RPE 7 | Around 3 reps remaining |
| 2 RIR | RPE 8 | Around 2 reps remaining |
| 1 RIR | RPE 9 | Around 1 rep remaining |
| 0 RIR | RPE 10 | No more reps possible |
This relationship isn’t an exact mathematical formula. Both RPE and RIR depend on your own assessment.
The practical difference is mainly how you think about the effort. For many athletes, asking “How many more reps could I have done?” during a traditional strength set is easier to answer than deciding whether the set felt like a 7, 8 or 9.
Which system works better therefore also depends on which one helps you judge your training intensity more accurately.
How Many Reps in Reserve Should You Leave?
The short answer: It depends.
Not every set needs to end at 0 RIR. At the same time, a working set that’s supposed to be challenging probably shouldn’t regularly end with six or seven reps left in the tank.
How many Reps in Reserve make sense depends on factors such as your training goal, the exercise and where you are in your workout.
Reps in Reserve for Hypertrophy
If your goal is muscle growth, your sets need to be challenging. But that doesn’t mean every set automatically needs to reach muscular failure.
In many cases, you can create an effective training stimulus while still having a few repetitions left. Around 1 to 3 RIR can therefore be a practical target for many working sets. That’s in line with a meta-analysis by Refalo et al. (2023): sets taken close to failure support hypertrophy, but reaching actual failure isn’t required.
There’s an important benefit to this approach: You can train hard without completely exhausting yourself on every set. This often makes it easier to maintain training quality across multiple sets.
That doesn’t mean 0 RIR is always wrong. Training to failure can have a place for selected exercises or individual sets. But it should be a deliberate choice rather than the automatic goal of every set.
RIR for Heavy Compound Exercises
With heavy Squats, Deadlifts or Presses, there’s another reason to leave some reps in reserve: technique and fatigue.
A heavy Back Squat set at 1 or 2 RIR can already provide a strong training stimulus. You don’t necessarily need to keep going until you physically can’t stand up from the next Squat.
As fatigue increases during complex exercises, your technique may also begin to deteriorate. A set can therefore be worth ending before your muscles reach complete failure.
RIR for Accessory Work
With less complex accessory exercises, you can often train closer to your limit.
A set of Biceps Curls, Lateral Raises or Triceps Extensions at 0–1 RIR places very different demands on your technique and overall fatigue than a heavy set of Back Squats or Deadlifts.
Your RIR target therefore doesn’t need to be identical for every exercise. What matters is the training stimulus you want to create and the additional fatigue that comes with pushing further.
How to Use RIR in Functional Fitness
Reps in Reserve come from strength training – and that’s exactly where they’re particularly useful in Functional Fitness.
A Strength session might include a prescription like:
4 × 6 Back Squats @ 2 RIR
Instead of prescribing one fixed weight, you choose a load that allows you to complete six reps while still having around two technically clean repetitions left.
You can use the same principle for movements such as:
- Squats and Deadlifts
- Strict Press and Bench Press
- Strict or weighted Pull-ups
- Dumbbell and Barbell accessory exercises
- Unilateral strength exercises such as Bulgarian Split Squats
RIR becomes particularly useful when your daily performance fluctuates. Maybe you completed six Back Squats at 90 kg with 2 RIR last week. Today, those same 90 kg already feel unusually heavy after four reps.
Instead of forcing yourself to stick to the number on the bar, you can adjust the weight and still achieve the intended training stimulus.
Does RIR Work for AMRAP, EMOM and For Time Workouts?
This is where things get more complicated.
During a traditional strength set, you have a clear start and finish. Once the set is over, you can estimate how many additional reps you might have been able to perform.
In a 15-minute AMRAP, your performance is also influenced by pacing, rest periods, breathing, different movements and increasing overall fatigue. The question “How many reps did I have left?” becomes much harder to answer.
The same applies to an EMOM. It may be more useful to look at whether you can consistently complete your prescribed reps within the available time than to assign an RIR value to every round.
RIR isn’t a universal tool for controlling the intensity of every Functional Fitness workout. Its biggest strength is in Strength and Accessory sessions where you can manage individual sets.
For Metcons, other tools such as pacing or RPE are often more useful.
How to Get Better at Estimating RIR
The idea behind Reps in Reserve is simple. Applying it accurately is harder.
After all, how do you know whether you really had two reps left if you never actually performed them?
Especially when you’re new to RIR training, your estimate can be quite far off. A set might feel hard enough that you think you only had one rep remaining. If you actually continued, you might discover that you could have completed another four. Research shows that these estimates are often inaccurate – especially when you’re still far from failure.
That doesn’t mean RIR doesn’t work for you. Estimating Reps in Reserve is a skill that improves with practice.
1. Learn the Difference Between Hard and Maximal
Just because a set feels uncomfortable doesn’t mean you’re at 0 RIR.
Burning muscles, an elevated heart rate or a strong desire to put the bar down don’t automatically mean you couldn’t perform another technically clean repetition.
Instead of only asking how unpleasant the set felt, try to judge what you were still physically capable of doing.
2. Pay Attention to Rep Speed
In many strength exercises, your final reps become slower as you approach your limit.
If the eighth rep of your Squat set moves just as quickly and smoothly as the third, you probably still have quite a few reps in reserve. If you have to grind through the final rep and the upward phase becomes noticeably slower, you’re probably much closer to your limit.
Rep speed isn’t a perfect RIR calculator, but it can give you another useful clue.
3. Compare Your Estimate With Your Actual Performance
Occasionally, you can take a suitable set closer to failure and see how accurate your previous estimate was.
If you think you have two reps left after rep eight but then comfortably complete another five, you know you’ve been underestimating your RIR.
You don’t need to take heavy Squats or Deadlifts to absolute failure to practice this. Less complex exercises are much better suited to developing a feel for your actual Reps in Reserve.
4. Track Your Sets
RIR becomes even more useful when you don’t look at each value in isolation.
If you track your weight, reps and RIR for the same exercise over several weeks, you can get a much clearer picture of your progress.
For example:
3 × 8 at 50 kg @ 2 RIR
might become:
3 × 8 at 55 kg @ 2 RIR
a few weeks later.
You’re lifting more weight at a similar perceived level of effort – a pretty good sign that you’ve become stronger. That’s what progressive overload looks like in practice.
RIR Training: More Than Just Weight and Reps
Weight, reps and sets tell you what you did. Reps in Reserve also help you understand how challenging that work actually was for you.
You don’t need to take every set to failure, and you don’t need to estimate your RIR perfectly down to the exact rep. What matters is developing a better sense of your limits over time and using that information to make smarter training decisions.
And if you’re looking for new Strength or Accessory sessions, check out the SmartWOD Workout Generator to find workouts based on your available equipment or build your own. Then use RIR to make sure the load matches what your training actually calls for.
