How to squat: technique, depth and which variation

Squat at least until the tops of your thighs are level with the floor. Go deeper if your whole foot stays down and your lower back stays still. In two small trials, deeper squats built as much or more muscle than shallower squats.^[1][2] In three, they built more strength at full depth.^[1][2][3] Your knees can travel past your toes. That's normal.^[4][5]

For the variation, pick the one you can take through a full range with control. The main versions differ in where they put the load, and that changes how upright you stay.^[6] We found no trial that compared them for muscle growth over weeks of training.

The answer isn't obvious because gym advice pulls two ways. One camp says deep squats wreck your knees. The other says deeper is always better. The studies back neither one.

If you've never squatted before, read learning the lifts first. It shows how to learn any lift with a light weight.

Why depth and setup matter

Two things tend to go wrong. The first is cutting the squat short. Half squats let you lift more weight, so it's tempting to cut depth.^[3] But in the trials below, training with shallower squats raised the full squat far less than training deep did.^[1][2]

The second is fear. Some advice says to keep your knees behind your toes.^[4] In a lab, that habit moved stress off the knees and onto the hips, and made people lean further forward.^[4]

What the research says

Squat depth is usually described by how far your knees bend. A half squat stops around a 90° knee bend (a right angle). A parallel squat stops when the tops of your thighs are level with the floor. A full or deep squat goes below that.^[6][7] Trials set these depths at different knee angles, so treat each trial's numbers as rough.^[9]

Range of motion is how far a joint moves during a rep. Your 1RM, or one-rep max, is the most weight you can lift once. Hypertrophy means muscle growth: the muscle fibres get bigger. A randomised trial puts people into groups by chance, so the comparison is fair. A meta-analysis pools the results of many studies on the same question into one estimate.

Full range in general: a bit more strength

Across all kinds of lifts, training through a full range built more strength than partial reps. That's the view of the American College of Sports Medicine (ACSM) 2026 position stand, an official summary of the evidence by an expert panel.^[8] Moderate evidence. For muscle size, the panel said there wasn't enough data to decide.^[8] A 2023 meta-analysis of 23 studies found about the same growth with full and partial reps.^[9] But the squat trials below found as much or more growth with deeper squats.^[1][2] Mixed evidence. The full story, including which half reps still count, is in choosing exercises and using full range of motion.

Deeper squats built as much muscle or more

An older 12-week trial in 17 male students found something different for the front thigh.^[2] One group squatted deep, to a knee bend of about 120°. The other squatted shallow, to about 60°, which is much higher than a half squat. The deep group's front thighs grew more. Their cross-section (the area of a slice through the muscle) rose by 4–7%, more than the shallow group's.^[2]

So the two trials disagree on the quadriceps. Mixed evidence on the front thigh. On the glutes and inner thigh, one trial favoured deep squats. Limited evidence. In neither trial did the deeper squat do worse.

In the 10-week trial, squats didn't grow the hamstrings (the back of the thigh) at either depth. Nor did they grow the rectus femoris, the one front-thigh muscle that also crosses the hip.^[1] Limited evidence. Squats train a lot of leg, but not all of it.

You get stronger at the depth you train

Both trials tested strength at both depths. In the 10-week trial, the full-squat group raised their full-squat 1RM by 31.8%. The half-squat group raised it by 11.3%.^[1] On the half squat, the two groups improved by 24.2% and 32.0%, and the study couldn't detect a difference between them.^[1]

The 12-week trial found the same pattern. The deep group got about 20% stronger at both depths. The shallow group gained 36% on the shallow squat, but only 9% on the deep one.^[2] The 2023 meta-analysis found this across many lifts: you test best at the range you trained, though the benefit may be smaller than people assume.^[9] Moderate evidence. A big half-squat number doesn't mean a big full squat.

A third trial put 53 men who already lifted into four groups for 10 weeks: full squats, parallel squats, half squats, or no squats.^[3] All three squat groups used the same share of their max, rising from 60% to 80% of their 1RM. Only the depth differed.^[3]

• The full-squat group was the only one that got stronger at all three depths.^[3]
• The parallel-squat group came second.^[3]
• The half-squat group showed no clear gain in strength or performance.^[3]
• Pain rose in all three squat groups, most in the half-squat group. Only the half-squat group reported more stiffness.^[3]

Limited evidence. It's one trial, and pain was scored with a questionnaire. It doesn't show that half squats cause pain, or that full squats prevent it.

Are deep squats bad for your knees?

We found no study showing that deep squats injure healthy knees.^[7][10] But the reviews disagree on what happens to knee forces as you go deeper.

A 2013 review looked at models and measurements of knee joints from donated bodies.^[10] Pressure behind the kneecap peaked around a 90° bend, and it was lower deeper than that.^[10] The authors concluded that deep squats don't raise the risk of injury to the knee's passive tissues (the parts that don't contract, such as ligaments). Their condition: you learn the technique under expert supervision and raise the load gradually.^[10] Expert consensus. This is the review authors' view, not a tested finding.

An older review from 2001 saw it differently. In the studies it covered, forces in the knee kept rising as the knees bent further, and peaked near the deepest point.^[11] For healthy knees, it recommended the parallel squat over the deep squat. Its reason: the risk to the knee's ligaments and cartilage pads "may" rise with depth.^[11] It also found the parallel squat was not harmful to a healthy knee.^[11] A 2024 review agrees that the squeezing force in the knee rises as you squat deeper.^[6]

None of these reviews reported injury data showing that deep squats harm healthy knees.^[6][10][11] The authors of a 2014 squat review found no known evidence that going below parallel raises the risk to the knee's ligaments and cartilage.^[7] Mixed evidence on knee forces.

Knees past your toes is normal

One lab study had 7 men who lifted do parallel squats two ways.^[4] In one, a barrier stopped their knees from moving forward. Blocking the knees cut the turning force at the knee by about a fifth. But the turning force at the hip rose about tenfold, and the men leaned their upper body further forward.^[4] The authors suggested the knees may need to move slightly past the toes to share the load well.^[4] Limited evidence: one small study that measured forces, not injuries.

A 2018 review of powerlifting injuries found no evidence that knees travelling forward lead to knee pain.^[5] The 2014 squat review found no known point where the risk of knee travel outweighs the benefit. It adds that trying to stop it increases forward lean.^[7] Expert consensus. If you're recovering from a knee problem, your physiotherapist decides this for you.

Which variation: what each one changes

Where you hold the weight changes your posture. A front squat puts the barbell across the front of your shoulders. A goblet squat puts one dumbbell at your chest. With the weight in front, your upper body stays more upright.^[6] A back squat (barbell across the upper back) usually leans you further forward. Leaning forward moves work from the knees to the hips.^[6] More forward lean has also been linked to more strain on the lower back.^[5] Expert consensus. This is the review authors' reading of lab data, not a training trial.

One lab study compared back and front squats in 15 trained people.^[12] The front squat worked the muscles about as hard as the back squat, with less compression on the knee.^[12] Limited evidence. It was one session, and it measured muscle activity, not growth. We found no trial that compared the two over weeks of training.

We found no training studies of the goblet squat on its own. It's a common way to learn the movement, because the weight in front helps you stay upright. This is coaching practice, not a tested finding.

Machines are a fair option too. Coaching practice. Free weights versus machines has its own section in gym basics.

What about the lower back?

Many lifters see their lower back round at the bottom of a deep squat. Lab work suggests a rounded lower back handles heavy loads less well than a straight one.^[6] But a review of squat injuries found no articles reporting injuries to the lower or middle spine from the squat.^[5] Limited evidence: lab measurements, not injury data. We found no study showing that the rounding is harmful, or that it's harmless.

How to apply it

Most advice on safe squat technique rests on assumptions from lab measurements, not on studies that counted injuries.^[5] Below, each step says whether it comes from an expert checklist or from coaching practice.

Before your first set: watch it

Watch a demonstration of the squat before you try it. Exercises in the Gymbers app come with a video, which you can save to your phone.

How to set up and do each rep

These first steps come from a 2014 back-squat checklist by strength researchers.^[7] This is the authors' view, not a tested finding.

1. Set your feet. Heels about shoulder width apart, toes forward or turned slightly out.^[7]
2. Brace. Before each rep, breathe in most of the way, about 80% of a full breath, and hold it.^[7] Bracing means using that held breath to stiffen your trunk so your spine stays steady.^[7]
3. Keep your whole foot on the floor. Heels and toes stay down for the whole rep.^[7]
4. Keep your knees in line with your feet. Don't let them cave inward.^[7]
5. Chest up, eyes forward.^[7]
6. Lower at a steady, controlled speed.^[7]
7. Reach at least parallel. The tops of your thighs end level with the floor, or lower.^[7]

The rest of the list goes beyond that checklist. Coaching practice.

• Let your knees travel forward. They can pass your toes.^[4]
• Find your depth. Go as deep as you can while your heels stay down and your lower back stays still. That's usually at or below parallel.
• Use a box to learn it. Set a box or bench at parallel height and touch it lightly on each rep.
• Can't reach parallel with your heels down? Try a goblet squat, or stand with your heels on small plates. Raising the heels lets the knees travel further forward.^[6]
• Ramp up first. Do two or three lighter sets that climb to your working weight, as in how to warm up.
• Film one set from the side, at hip height. Check that every rep reaches the same depth.
• Add a hamstring exercise. Squats didn't grow the hamstrings in the trial above.^[1] A seated leg curl or a Romanian deadlift covers them.
• Later, add some heavier sets. Once every rep looks the same, add some sets of about 3–6 reps. In the ACSM review, heavier weights built more strength.^[8] See rep ranges and load.

A worked example

Here's a 90 kg beginner learning the squat. The numbers are an example, not from a study.

• Weeks 1–2: goblet squat to a box at parallel. 12 kg × 8, 8, 8. On the clip, his heels lift on the last reps. He puts small plates under his heels.
• Weeks 3–4: 16 kg × 8, 8, 8. Heels stay down. Every rep touches the box.
• Week 5: back squat with the empty bar. Two ramp-up sets, then 20 kg × 8, 8, 8. Same depth on every rep.
• Week 6 onward: add 2.5 kg when every rep reaches the same depth. By week 10 he's at 35 kg × 8, 8, 7.

What's practical versus ideal. Deeper did as well or better for muscle and for full-depth strength in the trials.^[1][2][3] We found no trial that tested going deeper than you can control. So "as deep as you can control" is the rule, not "as deep as possible". Coaching practice.

Common mistakes

Cutting depth to lift more. A heavier half squat feels like progress. But in two trials, training with shallower squats raised the full squat far less than training deep did.^[1][2] Take some weight off and squat to parallel.

Keeping your knees behind your toes. It's old gym advice, and it sounds safe. In the lab it shifted stress to the hips and tipped people forward.^[4] Let your knees move forward.

Chasing depth you can't control. More depth looks better, so people sink until their heels lift or their lower back rounds. Stop just above that point. Coaching practice.

Treating squats as the whole leg day. The squat is a big lift, so it feels like enough. It didn't grow the hamstrings in the 10-week trial.^[1] Add a hamstring exercise.

How Gymbers fits

The Gymbers app can add warm-up (ramp-up) sets before your working sets, and you can log your warm-up sets too. The log records the weight and reps of every set, and last session's numbers sit beside each set. Each exercise has its own history and charts, and the app estimates your 1RM from your logged sets with the Epley formula.