Babies do develop at very different speeds, so there isn’t an exact answer to this question. Also, between a child’s first starting to stand or take a step, and really walking independently, there can be quite a long gap, so you have to include the whole lengthy process of learning to walk as well.
Very generally, babies usually take a few steps before they reach their first birthday. However, before that there will have been a whole series of movements at earlier ages, and parents and health professionals are told to look out for each of these. For instance, babies start trying to sit up and roll over usually when they are 4 or 5 months old, and by about 8 months their head and neck muscles should be strong enough for them to sit up safely by themselves. Once they are sitting up safely, babies then start to crawl, though it may be a couple more months before they are really doing this. Some babies tend to pull themselves around on their behinds more than crawling, and in those cases they may also start to walk a bit later than babies who start crawling earlier. So if your baby is a little later than most with these earlier developmental milestones, it is quite possible that walking may start a bit later too – but if he mastered sitting, rolling, crawling and standing eventually, usually you would expect him to be fine with walking too, albeit a little slower than the average. If he was late with any of these earlier stages, usually your health visitor will have checked that everything was OK.
From standing (and being able to sit down again without help, which is another stage in itself) and perhaps taking a few steps at a year old (some do walk quite independently before their first birthday, but again this isn’t typical) babies move to the toddling stage. This is so called because the baby isn’t quite steady on her feet at this point. There are several stages within this toddling stage – the baby will take just a few steps at first, perhaps go back to crawling, and will need someone to hold his hand for a while – but by about 15 months, a baby that took some steps at the age of 1 is likely to be able to walk.
It’s not unusual, and certainly nothing to worry about, for this process to take 17 or 18 months. This is especially likely if your baby was slower at the earlier stages, tended to move around by what is sometimes called ‘bottom shuffling’ or was born prematurely, which can also mean delayed development at the start of life. However, to be on the safe side it is recommended that you ask the doctor or health visitor about your child’s progress if he isn’t walking at 15 months, though you will almost certainly be told that this is perfectly normal. If she isn’t making progress after 18 months, all is probably still well, but your doctor may recommend an examination and if not, you should ask him/her if all is well. This timeline can give you more detailed information.
There are many reasons why a baby may not be walking after 18 months. These could include some illnesses or problems in the past, which have slowed down her development for the moment. There may also be something in the family history which affects development; or a number of other causes. In most cases it will just be a question of time until he walks, but your doctor will need to have a good look and probably ask you some questions in order to make a diagnosis, so it’s important to make an appointment and set your mind at rest.