It’s not unusual to feel confused and overwhelmed when you step into the weight room if it’s been awhile — or if you’re completely new to it. One question that commonly crops up is: How do I know how much weight to lift?
If you’ve found yourself asking this question, rest assured the answer isn’t too complex. But before we can get into the specifics, you need to identify your strength-training goal, as it will determine how many reps you’ll perform, which will then dictate how light or heavy to go with the weights.
Here’s a breakdown of the most common strength-training goals:
This is a great goal to start with if you’re a beginner or returning to exercise after a long hiatus. If you’re working toward general fitness, stick to 3 sets of 8–12 reps, says manual therapist Johnny Tea, certified strength and conditioning specialist and founder of JT Strength Therapy in Pasadena, California.
When chasing pure strength, your best bet is to lift heavier loads for 1–6 reps. It’s important to build a strong foundation and know how to lift with proper form before you go heavy, so make sure you’ve been lifting consistently 2–3 times per week for at least six months before working within this rep range.
If you’re hoping to increase muscle size, your available rep range is a lot wider than previously thought. In the past, the standard recommendation for packing on muscle was to lift moderately heavy loads for 6–12 reps. Now, a review in the Journal of Strength and Conditioning Research suggests you can build muscle just as effectively by lifting a heavier load (greater than 60% of your one-rep maximum or the most weight you can lift for a single rep) as lifting a lighter load (less than or equal to 60% of your one-rep max). The key is to take your sets within a rep or two of muscular failure or the point where your form begins to break down.
To improve the ability of your muscles to contract repeatedly over longer periods of time, you’ll want to perform sets of 12–20 reps with a lighter weight. You can also try exercise classes like barre and yoga, where you hold poses for longer periods of time (typically 60 seconds) using only your bodyweight, says Ashley Walter, a personal trainer and healthy living expert in Chicago.
Once you’ve ID’d your strength-training goal and target rep range, you can then set out to determine how much weight to lift.
For simplicity’s sake, Tea recommends using a 1-to-10 rating of perceived exertion (RPE) scale. When rating your perceived exertion level, or how hard you feel like your body is working, think of 1 as no effort and 10 as maximum effort. Within this range, Tea suggests aiming for a weight that feels like an 8. When you lift a load at a perceived exertion level of 8, you end your set feeling like you could have performed two more reps.
If you can perform 1 or 2 reps over your desired number, the American College of Sports Medicine recommends increasing weight by 2–10%. So, if you can squat 135 pounds for one or two reps over the target number, increase the weight to 137.7–148.5 pounds. On the other hand, if you’re struggling to complete your set, go lighter.
Intermediate-to-advanced lifters may periodically test their one-rep maximum for bigger lifts like squats, bench presses and deadlifts to gauge strength progress and help determine how much weight to lift. For example, if you know you can squat 135 pounds for a single rep, chances are you could lift a “light” load (equal to or less than 60% of your one-rep max) of 80 pounds for roughly 12 reps.
However, Tea prefers to use the RPE scale over percentages, as there are many factors — like sleep, nutrition, stress and overall recovery — that determine how much you can lift on any given day. “Let’s say someone did a goblet squat with a 35-pound dumbbell,” he says, “that might typically be an 8 for that person, but if they got a really bad night of sleep, that 35 pounds might actually feel like an 11.”
Whether you’re lifting for a one-rep max or banging out reps of bodyweight exercises, you need to focus on doing it with proper form.
If you’re not sure what correct form looks or feels like, seek professional help — especially if you’re a beginner. “I firmly believe that, in order to be as safe as possible, people should start with someone who can help them with form and breathing and then send them away with a program that they can do on their own after they feel comfortable enough,” Walter says. She recommends meeting with a trainer at least 3–4 times to nail proper lifting form.
What’s more, your form needs to be on-point before you add more weight. While lifting any weight with good form is critical for injury prevention, it becomes even more important the heavier you go. “If your form is inadequate, your body starts to compensate, and that might not mean you get injured right off the bat, but eventually your body will start to break down as you put on more weight or move on to more challenging exercises,” Tea says.
Even as you become more advanced, it’s a good idea to work with a partner whenever possible, particularly when you attempt heavy lifts. “Spotters are key to holding you accountable and keeping you safe as you push your weight,” Walter says.