How much weight should I lift?
On this page
Enough that the last two or three reps of each set are hard but still clean, with two or three more left in you. For strength, work toward a weight you can lift about 5 to 10 times, which is roughly 75 to 86% of your max. The reps you have left tell you more than the number on the plate.
Most people pick a weight by feel, by fear, or by copying the person on the next bench. Some go light forever because they’ve heard light weights “tone” and heavy ones bulk you up. Others max out on day one to find their number. The first group never gives their muscles a reason to change, and the second takes on a max attempt for a number they don’t need.
What we’d do
Judge the weight by the reps you have left, never by the number on it. Stop each set when two or three more reps would still be possible. If you finish a set and could have done five more, it was too light. If your form breaks before the last rep, it was too heavy. Start the big lifts around 10 reps and work down toward 5 to 8 as you get used to them.
It’s like the right pace on a run
The right weight works like the right pace on a hard run. You could still say a short sentence, but you couldn’t sing. If it’s too easy, nothing changes. If you go all out, you’re done for the day after one set. Lifters call that gap “reps in reserve”, and the 2026 position stand from the American College of Sports Medicine (ACSM) suggests aiming for two or three.
How heavy is heavy?
The ACSM’s review of 137 reviews found strength rose most with loads of 80% of your max or more. You don’t need to know your max to use that. The reps you can do tell you roughly where you are:
| Reps you can do | About this much of your max | What it builds |
|---|---|---|
| 5 | 86% | Strength, the most |
| 8 | 79% | Strength and muscle |
| 10 | 75% | Muscle, and strength |
| 12 | 71% | Muscle, and learning a new move |
The percentages come from Epley’s formula, the one most calculators use. People really do vary, though. A 2024 review of 269 studies and 7,289 people found big differences between individuals at the same percentage, and more reps on the leg press than on the bench press. Sex, age and training made little difference. Use the table as a starting point and let your own reps correct it.
Light weights build muscle too
Light and heavy, both to failure
21 studies. Schoenfeld and others, Journal of Strength and Conditioning Research, 2017
When every set was taken to failure, muscle grew about the same with light loads (60% of max or less) as with heavy ones. Heavy loads raised the one-rep max more.
Light sets only work when you take them very close to failure, which takes a lot of reps.
Failure isn’t needed
15 studies. Grgic and others, Journal of Sport and Health Science, 2022
Stopping a couple of reps short built the same strength and muscle as going to failure, when the total work was matched.
Short of failure means two or three reps short. Ten reps short isn’t the same workout.
That’s why the advice has two parts. Heavier weights are the fastest route to strength, and any weight works for muscle as long as the set ends close to hard.
Find your weight in one session
- Pick a weight you think you could lift 12 times.
- Do 8 to 10 reps, then stop. Ask yourself how many more you had.
- If you had more than four left, go up a step on the next set.
- If you had two or three left, that’s your weight.
- If you had none left, or your form broke, go down a step.
- Write it down, so next time starts where this one ended.
Say you can squat 135 lb (61 kg) for 8. The one-rep max calculator puts your max at 162 to 172 lb, most likely about 169. A heavy set of 5, at about 86%, would be around 145 lb (66 kg). You found that without ever lifting a max.
When to go up
Once every set hits the top of your rep range with clean form, add the smallest step you can. When should I add weight? walks through it. Over 60, or brand new, there’s no reason to test a true max at all. The calculator gives you the range from any set of 12 or fewer.
5 sources
- Currier BS and others, ACSM position stand on resistance training, Medicine and Science in Sports and Exercise, 2026pmc.ncbi.nlm.nih.gov
- Schoenfeld BJ and others, Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis, Journal of Strength and Conditioning Research, 2017europepmc.org
- Nuzzo JL and others, Maximal number of repetitions at percentages of the one repetition maximum: a meta-regression and moderator analysis of sex, age, training status, and exercise, Sports Medicine, 2024pmc.ncbi.nlm.nih.gov
- Grgic J and others, Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy, Journal of Sport and Health Science, 2022pmc.ncbi.nlm.nih.gov
- One-repetition maximum, Wikipediaen.wikipedia.org
