What an upper lower split is
The split is exactly what it sounds like. Upper days train chest, back, shoulders, and arms. Lower days train quads, hamstrings, glutes, and calves, plus core if you want it. Abs can go on either day. The structure is simple enough to memorize after one week, which is part of why it has survived decades of training trends.
Most people run it 4 days per week: upper, lower, rest, upper, lower, then two rest days. Each muscle group gets about 48 to 72 hours of recovery before it trains again. That frequency, twice per week per muscle, is where research and decades of gym experience agree the best growth happens for intermediate lifters.
The classic 4-day schedule
Monday is upper, Tuesday is lower, Wednesday is rest, Thursday is upper, Friday is lower, and the weekend is rest. If your week looks different, keep the pattern and shift the days: what matters is the upper, lower, rest, upper, lower rhythm, not the calendar names.
There is also a 3-day version for busier weeks: week one goes upper, lower, upper; week two goes lower, upper, lower. Each muscle still gets trained 3 times every 2 weeks. And lifters with 5 or 6 days can add a second lower day or a full-body day, though at that point a push pull legs rotation is usually simpler.
Sample upper day
A solid upper session hits one heavy chest movement, one heavy back movement, one overhead press, one more back movement, and one exercise each for biceps and triceps. For example: barbell bench press 3 sets of 6 to 8, bent-over row 3 sets of 8 to 10, overhead press 3 sets of 8 to 10, lat pulldown 3 sets of 10 to 12, dumbbell curl 2 sets of 10 to 12, and triceps pushdown 2 sets of 10 to 12. That is 16 total sets, which takes most lifters 60 to 75 minutes.
Run two upper days with slightly different flavors. Day one leans heavy: bench press and rows in the 6 to 8 rep range. Day two leans moderate: incline dumbbell press and pull-ups or pulldowns in the 8 to 12 range. Same muscles, different stimulus, and the variety keeps progress moving.
Sample lower day
A lower session needs one squat pattern, one hinge pattern, one single-leg or machine movement, and calves. For example: back squat 3 sets of 6 to 8, Romanian deadlift 3 sets of 8 to 10, leg press 3 sets of 10 to 12, lying leg curl 2 sets of 10 to 12, and standing calf raise 3 sets of 12 to 15. That is 14 total sets and about an hour, since lower-body sets need longer rests.
As with upper days, vary the two sessions. Day one: squat heavy, hinge moderate. Day two: hinge heavy with deadlifts or heavier Romanian deadlifts, squat moderate with front squats or leg press. The pattern is the same, the emphasis flips.
Weekly volume check
Two upper days at 16 sets each is 32 upper-body sets per week. Chest gets direct work on both days: roughly 6 to 8 hard sets per week, right in the productive range for growth. Back gets 12 sets across rows and pulldowns on each day, 24 total, which sounds like a lot until you remember the back is several muscles sharing the work. Run these numbers for 8 to 12 weeks, add weight when you hit the top of your rep ranges, and take a lighter week when progress stalls for two weeks straight.
Upper lower vs push pull legs vs full body
Push pull legs needs 5 to 6 days to hit everything twice, so it suits lifters with wide-open schedules. Full body 3 days a week suits beginners and busy lifters, but sessions get long once you are strong enough to need real volume. The upper lower split sits in the middle: 4 focused days, each under 75 minutes, every muscle trained twice. For the large middle of lifters training 4 days a week with size and strength goals, it is the default answer for a reason.
Pick based on your honest weekly availability. The best split is the one you can run for 12 straight weeks without missing days. Four days you actually complete beats six days you half-finish.