Sitting up usually happens in two stages. First your baby sits with support, propped by your hands or cushions, or leaning forward on their own hands. Then they sit steadily on their own and, a little later, get themselves into sitting. The CDC's 6-month checklist says most babies (75% or more) lean on their hands to support themselves when sitting by 6 months, and its 9-month checklist says most sit without support and get into a sitting position by themselves.
The World Health Organization's motor development study of healthy babies in five countries found the normal window for sitting without support ran from 3.8 to 9.2 months, with half sitting alone by about 5.9 months. Sitting was the narrowest of the six motor windows it measured, and every baby in the study sat alone by 9 months.
When do babies sit up? Ages at a glance
| Age (corrected) | What sitting often looks like |
|---|---|
| About 4 months | Holds head up with little support when gently pulled to sit |
| About 5 months | May try to sit for short moments but still needs your hands for support |
| By 6 months | Leans on hands to support themselves when sitting (CDC); many sit with support |
| About 7 months | Many sit on their own for short periods |
| About 8 months | May sit well with little or no support and pull themselves into sitting |
| By 9 months | Sits without support and gets into sitting alone (CDC) |
The 4-, 5-, 7- and 8-month rows come from Pregnancy, Birth and Baby's month-by-month pages for 4 months, 5 months, 7 months and 8 months. The AAP says that by about 6 to 8 months, many babies placed upright can stay sitting without leaning forward on their arms.
What's the difference between supported, tripod and independent sitting?
| Type | What it looks like | Typical timing |
|---|---|---|
| Supported sitting | Sits upright with your hands, your lap or cushions holding them | Around 5 to 6 months |
| Tripod sitting | Sits leaning forward on straight arms, hands on the floor for balance | Most by 6 months (CDC) |
| Independent sitting | Sits upright without using hands, and can reach for toys | Many by 6 to 8 months; most by 9 months |
| Getting into sitting | Moves from tummy or crawling into sitting without help | Most by 9 months (CDC) |
The AAP notes it takes some time after sitting with support before babies can get themselves into a sitting position. Getting into sitting usually comes after they can hold the position.
How does sitting develop, step by step?
- Head control. By about 4 months, Pregnancy, Birth and Baby says most babies hold their head up with little support when gently pulled to sit.
- Push-ups on the tummy. Pushing up onto forearms is on the CDC's 4-month list, and pushing up on straight arms is on its 6-month list.
- Supported sitting. Your baby sits with your hands or cushions, at first only briefly.
- Tripod sitting. Leaning forward on their hands, your baby starts holding themselves up.
- Sitting freely. Their back straightens and their hands come up to play.
- Getting in and out. Your baby moves between sitting, tummy and crawling on their own.
How can I help my baby learn to sit?
- Keep up tummy time. Pregnancy, Birth and Baby says tummy time builds strength for rolling, sitting and early movement. See our tummy time guide.
- Practise supported sitting. The CDC suggests holding your baby up while they sit and offering toys while they practise balancing. The AAP suggests supporting their back with pillows as they learn.
- Put interesting toys in front. The AAP says toys placed in front give your baby something to focus on while they find their balance.
- Play on the floor every day. The CDC says floor play helps babies move, learn and explore.
- Try sitting your baby between your legs on the floor; many families find this gives gentle support and a soft landing.
- Gradually give less help as your baby gets steadier.
Your baby will topple, and that's part of learning. Pregnancy, Birth and Baby suggests placing cushions around them for a soft landing.
Do baby seats and bouncers help babies sit?
Seats that hold your baby upright can be handy, but they don't do the work of learning to sit. The NHS activity guide says long stretches in reclining carriers or seats that prop a baby upright can delay their ability to sit up on their own. It also says long periods strapped into a buggy, car seat or highchair aren't good for young children, and suggests breaks on long car trips.
The CDC's 4-month tips suggest limiting time in swings, strollers and bouncy seats so your baby has time to move and interact through the day. Short periods in a seat are fine; what helps sitting is lots of time on the floor.
Car seats are the exception: always use a properly fitted car seat for every car trip. See car seat safety.
How do I keep a baby who's learning to sit safe?
- Practise on the floor, with cushions around your baby, and stay close.
- Never put a bouncer, rocker or baby seat on a table, bench or bed. Pregnancy, Birth and Baby's falls prevention guide says to always place a rocker or bouncer on the floor and not to carry your baby around in it.
- Use the 5-point harness every time in the highchair, pram or stroller.
- Never leave your baby alone on a raised surface, such as a change table, bed or sofa.
- Check what's within reach. A sitting baby can grab more, so move small objects, cords and hot drinks away.
- Sleep is separate. Sitting supports and pillows are for awake play only. For sleep, your baby goes on their back on a firm, flat surface with nothing soft in the cot. See safe sleep.
If your baby was born early, Pregnancy, Birth and Baby's premature baby guide expects sitting with support at about 6 months corrected and sitting up alone at about 9 months corrected. It also lists sitting supported on your lap or in a highchair as one of the signs your baby is ready for solids. See starting solids.
What if my baby isn't sitting yet?
Babies learn to sit at different times, and the WHO window shows how wide the normal range is. Keep offering tummy time and supported sitting practice.
Call 999 now if your baby
- has difficulty breathing, has blue, grey or pale skin or lips, is very drowsy or hard to wake, or has a seizure (the NHS urgent help guide)
See a doctor promptly if your baby
- stops doing something they could do before, such as sitting or holding their head up
- seems unusually stiff or floppy, which the AAP lists as a sign to raise
Talk to your GP or health visitor if
- your baby isn't sitting by themselves by 9 months (corrected). The AAP's 8–12 month guide says to let your doctor know, and Pregnancy, Birth and Baby's 10-month page lists not sitting without support as a reason to talk to your doctor or health visitor
- your baby can't lean on their hands to support themselves when sitting by about 6 months
- your baby struggles with head control, or uses one side of their body much more than the other
What's worth writing down?
Note when your baby first sat with support, when they first sat alone for a few seconds, and when they could get into sitting by themselves. If you're concerned, a short video of your baby sitting on the floor shows your GP or health visitor more than a description can.
