If there's one adjective that describes babies in a nutshell, it's "needy". Babies need us for everything: eating, sleeping, changing, comfort, and that's just the start. It is one thing, conceptually, to know your baby needs you to change their diaper, but do you also have to be your baby's constant source of entertainment, too? Can't a parent catch a break? If you're in need of some reprieve and, as a result, asking yourself, "How old is a baby before they can play on their own?" know that you're not alone and, actually, some solo-play time for your kid is probably on its way. Little by little, however, babies start to reach milestones that allow them to do things more independently, including play.
When discussing independent play and children under the age of 1, of course no one is implying that any baby should be expected to play unsupervised for great lengths of time. As Parents thinking about what age their baby can play alone are usually thinking about it within the context of a supervised environment, with the parent nearby and keeping a close eye on the child. This is in contrast to the constant "Mommy Show" that a lot of parents feel pressured to be putting on 24/7.
It is also important to take into account developmental stages and milestones when thinking about what babies are capable of and how long they might be interested in a particular activity. According to Baby Center, it is not until the age of 3 months that babies are able to support their own heads, so the idea of leaving a baby alone on a play mat before the 3 month mark is probably unwise.
Some parents feel guilty about leaving their babies to play without them being the ones to constantly stimulate them. For example, a parent might see a baby quietly kicking at the toys in his play gym and looking around but worry that their baby is bored. But as What To Expect points out, babies at around the 3-month-mark are stimulated enough by the sights and sounds around them, that it doesn't take much to entertain them. Just being able to look at you while you go about your activities in the house, and listen to your voice, is more than enough entertainment for a child.
Every child develops differently, but as Healthy Children states, between the ages of 4 and 7 months is generally when babies start to develop increased perceptual and motor abilities (such as grasping, sitting up, and rolling over). These increased skills can lend themselves towards a child's ability to engage in their world in more fun and interactive ways. So for the times when a parent is not actively playing with their baby, for example, while the parent is responding to emails or preparing dinner, they could, as the American Academy of Pediatrics recommends, give their baby stacking toys such as nesting cups to play with.
It is also healthy for babies to learn how to play solo. As What To Expect notes, playing alone helps babies develop important skills like sitting, crawling, and cruising. What To Expect suggests the 7 month mark for introducing toys or play involving sounds like banging on a pot, or a ball that jingles. These are great toys for supervised independent play. Once babies have gotten the hang of a toy (after you've shown them how to play with said toy), What To Expect suggests you experiment with "leaving" the baby's line of sight for small, periodic amount of time. Tell your baby you are about to leave the room, do so, and then immediately come back in a fun game of "peek-a-boo" to show them that you're still there and that you always come back.
None of this is to say that independent play is the only game in town. Children learn the most from their interactions with other people, such as their parents and their peers. The American Academy of Pediatrics highlights the importance of solo play, and stresses the role it plays in a child's overall development and how it helps encourage healthy parent-child bonds. Dr. Kenneth Ginsburg of the Children’s Hospital of Philadelphia adds, in an article by Healthy Children, that independent play is an important part of a child's healthy and balanced life. “When children have a downtime, they’re going to fill that time with whatever fits their needs,” he says.
So, when thinking about helping your baby learn to play alone (i.e. with you nearby) for short amounts of time, start with baby steps (pun intended). Once you've taken into account what your child is capable of based on their perceptual and motor development, which will typically occur around the 7-month-mark, you can let the solo games begin!