How to choose weight for 5-8 rep range strength training (and every other set)

Here's how to choose weight for 5-8 rep range strength training, or any rep range: pick a load you can lift for the target reps with about two good reps left in the tank. Not the weight you lifted last month. Not the weight the person next to you is using. Not a number from a percentage chart you found at 1am. The weight that, today, leaves you two clean reps short of failure.

That's the whole rule. The rest of this post is how to find that weight quickly, how to adjust it between sets, and how to keep it moving up over weeks. If you'd rather never think about it, that's a job for a workout app built for more than one sport, one that also knows yesterday was intervals.

Start with the target, not the weight

Every set in a decent program has two parts: a rep target and an effort target. "3 x 5–8 at RPE 8" means three sets of five to eight reps, each stopped with about two reps in reserve. RPE 8 equals 2 reps in reserve on the lifting RPE scale; RPE 9 is one, RPE 10 is none (Zourdos et al., 2016).

The effort target is the important half. A set of 6 at RPE 6 and a set of 6 at RPE 9 are completely different workouts, even though they look the same in your notes. Only sets that are reasonably hard count toward your weekly volume, which is the core idea in how many sets per workout explained.

Most ready-made split templates will hand you both numbers. Your job is to find the load that matches them.

How to choose weight for 5-8 rep range strength training

The 5 to 8 range is the sweet spot for most strength work outside of competitive powerlifting: heavy enough to build real strength, light enough that form holds and you can do several good sets. Here's the method.

Step 1: Warm up in jumps

Start with the empty bar or a light weight for 8 to 10 easy reps. Then make three or four jumps toward your guess for the working weight, doing fewer reps each time:

These ratios are a coaching convention, not a law. The point is that by the last warm-up you'll already know whether your guess is heavy or light, because the bar tells you.

Step 2: Do one working set and rate it honestly

Do your first working set at your best guess. At the end, ask one question: how many more clean reps could I have done? Watch bar speed as well as feel. In the Zourdos study, slower reps went with higher RPE (Zourdos et al., 2016). If the last rep crawled, you were not two reps short.

Step 3: Adjust

Expect the reps in reserve to shrink across sets at the same weight as fatigue builds. If set one is a clean RPE 7 and set three is an honest RPE 9, that's normal. If set three falls below the rep range, take a little weight off.

Step 4: Write it down

The working weight you ended on is next session's starting point. Without a log, every session starts with a guess.

Why percentages are only a starting point

Plenty of programs prescribe sets as a percentage of your one-rep max. That works if your one-rep max is accurate and today is a normal day. The trouble is that the number of reps people can do at a given percentage of their max varies a lot.

A meta-regression of 952 reps-to-failure tests from 269 studies found the number of reps possible at a given percentage varied between individuals, and that people managed more reps on the leg press than the bench press across the loading range (Nuzzo et al., 2024). So the same percentage can be a comfortable set for one lifter and a grinder for another, and can feel different between lifts for the same person.

Effort-based loading handles that automatically. In trained men following an 8-week squat and bench program with matched sets and reps, choosing loads by RPE produced strength gains at least as good as fixed percentages, with a likely small advantage for the RPE group (Helms et al., 2018).

The practical version: if your program uses percentages, use them as a first guess for Step 2 and let the effort target decide the final weight.

The accuracy problem (and how to fix it)

Choosing weight by reps in reserve depends on being honest about reps in reserve, and most people aren't quite. A meta-analysis found lifters underpredicted their reps to failure by about one rep on average, with lots of variation. Predictions got slightly better closer to failure and on sets of 12 reps or fewer (Halperin et al., 2022).

That's good news for the 5 to 8 range: it's exactly where estimates are most accurate. Two ways to sharpen them:

1. ›Log reps in reserve on every working set for a few weeks.
2. ›Check yourself occasionally. On a safe exercise, a machine or a lift with a spotter, take the last set to failure and compare it with your guess. How often that's worth doing, and on which lifts, is covered in our guide to training to failure.

Adjusting for the goal

The method doesn't change across goals. The targets do.

Why strength work sits lower and heavier is the main point of what is hypertrophy vs strength. Why size work can use almost any rep range as long as sets are hard is covered in low reps vs high reps for muscle growth.

Two more situations that change the load:

• ›Tempo. A slow, controlled lowering phase makes the same weight harder. If your program prescribes a 3-second negative, start lighter than your normal working weight; eccentric vs concentric explained covers why.
• ›Short rest. In circuit training with weights, where you rotate exercises with little rest, pick loads clearly lighter than you'd use for straight sets with full rest. Fatigue carries over.

How to progress the weight

Use double progression, the method most beginner programs run on:

1. ›Pick a load you can lift for the bottom of the rep range at about RPE 7 to 8.
2. ›Each session, try to add a rep to each set at the same effort.
3. ›When you hit the top of the range on every set with clean form, add the smallest jump available and drop back to the bottom of the range.

On a 5 to 8 rep scheme, that means working from 3 x 5 up to 3 x 8, then adding weight and starting again at 5. Beginners can often move up every week or two. When that stops, you're not failing; you're no longer a beginner.

If you run, expect your leg numbers to wobble around hard running weeks. Let the effort target lead. A lighter squat at the right RPE the day after a long run is still the right session.

Common mistakes

Picking the weight before warming up. Your warm-up sets are free information. Use them.

Ego loading. If the bar speed dies on rep two and you grind to six, the weight was wrong, whatever the plan said.

Sandbagging. The opposite problem: everything at RPE 6 "to be safe". Those sets barely count.

Changing weight mid-set in your head. Decide, lift, rate, adjust. Then repeat.

Chasing a new kind of muscle. The sarcoplasmic vs myofibrillar hypertrophy argument, and the textbook question of hypertrophy vs hyperplasia, are interesting reading. It shouldn't change the load on the bar. Hard sets at the right effort do the work.

How exrsz chooses your weights

exrsz builds a periodized plan from your goal, schedule, level and equipment, with a rep and effort target on every lift. It balances your lifting against your running in the same plan, adapts each week to how you actually trained, and reshuffles missed sessions.

FAQ

How do I know what weight to lift?

Choose a weight you can lift for your target reps with about two clean reps left. Warm up in jumps, do one working set, rate how many reps you had left, and adjust the next set up or down.

What weight should I use for 5 to 8 reps?

A weight you can lift at least 5 times with good form and that leaves about 2 reps in reserve, roughly RPE 8. Start at 5 reps and add reps each session until you reach 8, then add weight.

Should I use percentages of my max?

As a starting guess, yes. The reps people can do at a given percentage vary between individuals and exercises (Nuzzo et al., 2024), so let the effort target set the final weight.

How do I know if a weight is too heavy?

If you can't reach the bottom of your rep range, your form changes, or the bar slows to a grind well before the last rep, it's too heavy for that set. Drop the weight a little and keep going.

Is it better to choose weight by RPE or percentage?

Both work. In trained men, RPE-based loading produced strength gains at least as good as percentage-based loading, with a likely small advantage (Helms et al., 2018).