The youngest baby to sit up is 4 months old.
However most babies sit up independently between 6 months to 9 months of age.
At 4 months babies can often hold their head steady without support.
At 6 months babies can sit with some help.
At 9 months babies can sit up well enough without support and can get in and out of a sitting position but may still require some help.
At 12 months babies can get into a sitting position without help.
You can help your baby learn to sit by giving your baby daily tummy time and allowing them to practice sitting while they lean against you.
Babies will begin sitting with support once the baby has good head and neck control, which is usually around 4 to 5 months of age.
And between the ages of 6 and 8 months old, babies will get the hang of sitting independently.
Then by 9 months of age, the baby will be able to get themselves into a sitting position.