How Many Sit-Ups Should You Do a Day? (And Whether You Should Do Them at All)
A daily sit-up number by level, how to split it, the honest case for swapping sit-ups for planks or crunches, and how to count core work so it actually adds up.
A reasonable daily sit-up target for most people is 30–60, split into 2–3 sets, with a hard ceiling around 100–150 unless you’re training for a test that requires more. Below that, how to pick your number — and the honest note that a lot of people are better served by planks and slow crunches than by big sit-up numbers.
By level
Test: one set of full sit-ups (shoulder blades to floor, up to vertical, feet unanchored or lightly anchored) until you can’t without yanking your neck.
| Max set | Daily total | Split | Add weekly |
|---|---|---|---|
| Under 10 | 15–20 (or crunches) | 3 × 5–7 | +1–2 per set |
| 10–25 | 30–50 | 3 × 10–17 | +2 per set |
| 25–50 | 50–100 | 3–4 × 15–25 | +5 per day |
| 50+ | 100–150, or go harder | 4 × 25–40 | Add difficulty |
Sit-ups vs crunches vs planks — which should you count?
Honestly:
- Sit-ups work the hip flexors as much as the abs and load the low back a bit. Fine in moderate volume for most people. If you have a cranky low back, they’re the first thing to swap.
- Crunches (shoulders off the floor, low back stays down) isolate the abs and are easier on the back. Slow, controlled crunches — 2 seconds up, 2 down — are underrated.
- Planks train the core to do what it actually does most of the day: hold still against load. Best carry-over to push-ups, squats, and posture. See the 30-day plank challenge.
A sensible daily core dose for someone who wants “abs that work” is 30–50 slow crunches or sit-ups plus 2 minutes of plank. Both are countable, which is the whole point.
Every day?
Yes, at these volumes. The abs recover quickly and daily moderate work is fine. Skip the day if your low back (not your abs) is sore, and never anchor your feet under something heavy and yank — that’s the version that hurts backs.
Form that keeps your neck and back happy
- Hands across the chest or lightly at the temples — never pull the head.
- Exhale on the way up. Chin slightly tucked.
- Roll up, don’t jerk. If you have to throw your arms to get up, that rep is too hard: switch to crunches or reduce range.
- Bent knees, feet flat. Unanchored is harder and more honest.
Count it
Core work is the classic “I’ll do some” exercise that turns into none. Set a daily number and log it. Tally on paper, or tap it into RepTrend — set the goal at 40, log 20 after breakfast and 20 before bed, keep the streak. The counting is what makes it a habit; the exercise choice is secondary.
Making core work harder instead of doing more
Past ~50 reps a set, more sit-ups mostly build endurance in the hip flexors. Instead:
- Slow tempo: 3 seconds up, 3 down. Halves the reps needed.
- Weighted crunches / sit-ups: hold a book or plate on your chest.
- Hanging knee raises or leg raises: 3 × 8–15.
- Hollow-body holds: count seconds, like planks.
- Ab-wheel rollouts: 3 × 5–10, brutal.
Fifty hard reps a day beats 300 sloppy ones, and it takes a fifth of the time.
Frequently asked questions
Is 100 sit-ups a day good?
It's a fine endurance target if your form is clean and your back is happy, but for most people 40–60 slow reps plus planks does more with less strain. Past 100, add difficulty rather than reps.
Will sit-ups every day give me a flat stomach?
They strengthen the abs, which can improve posture and how the midsection holds itself, but a flat stomach is mostly body fat. Sit-ups burn very little; diet does that part.
Are sit-ups bad for your back?
In moderate volume with good form (rolling up, no neck pulling, no heavy foot anchoring) they're fine for most healthy people. If you have a low-back history, swap them for crunches and planks.
How many sit-ups a day for a beginner?
Start with 15–20 a day in three sets, or crunches if full sit-ups aren't there yet, and add a rep or two per set each week.