21 Month Old Baby Milestones And Development – New Parents Guide


As you start seeing your toddler’s interests shine through in her game and toy choices playtime will start being more entertaining for both of you! Your little girl might like crashing toy trucks while your friend’s son digs pink heels! Babies don’t know about gender-specific toys at this age, they just want to have fun! And exactly that – having fun – is very important for reaching 21 month old milestones in time! 

Still, you will have to be more careful than you were ever before. Your little one will find it fun to stick small objects in her ears, nose, or mouth. Keep on reading to find out more about 21 month old development goals and milestones! 

What You Should Know 

  • Your baby is developing new tricks to show off as she continues to grow. Be supportive and encourage her to keep trying to learn new tricks and obtain new skills. 
  • Seeking approval is now a very serious thing. Your toddle will always expect you to give a reaction to her actions, so make sure you do, no matter if it is good or a bad one. 
  • Teething is now also a big part of your baby’s life.  Lower second molars are starting to erupt and your baby might experience some pain. This can lead to a lack of sleep for both of you. 
  • Odd behavior is still persistent but you’ve, fortunately, probably found ways to cope with it. Stay calm and be patient, it just takes some time for your baby to start understanding things better. 

Important 21 Month Old Milestones

According to the World Health Organization, the median height for boys this age is 33.5 inches and 32.9 inches for girls. When it comes to weight, the average numbers are 25.5 pounds for boys and 24.9 pounds for girls. If you can’t notice a huge difference in measurements in your child and other kids than you can be sure that she’s reaching 21 month old milestones for weight and height in time. 

21 Month Old Skills and Milestones 

These are some of the milestones that your baby will reach as she goes through the 21 month old development:

  • Speech – Babies usually know about 50 words by now. You can expect that she will start making two-word phrases soon, so stay supportive and try to teach her as many phrases as you can! 
  • Walking – Most children can run, throw a ball, squat, and stand on one foot at this age. Also, 21 month olds are starting to following more complicated instructions. For example: fill the bucket with toys and bring it to me. 
  • Potty Training – You might notice some potty training readiness signs in your toddler. If you truly feel he’s prepared you can start early with it, but only if you’ve previously introduced your baby to the topic. Keep in mind that it is still early to force our child to get rid of the diapers. Babies usually start to potty train when they’re about 2.5 years old. 
  • Teething – Expect teething discomfort as lower second molars are starting to erupt. Use teething toys whenever you can and hope that they will ease some pain. Be prepared for a couple of restless nights if the pain is unbearable for your baby. 
  • Behavior – Challenging behaviors are a normal part of a 21 month old development. Still, this doesn’t mean that you should ignore them. You need to learn how to deal with separation anxiety, tantrums, and approval hysteria. Your baby still can’t communicate everything she feels, so you need to find reasoning, stay calm, and deal with the situation. 
  • Autism – As the 2 year old checkup is coming soon, you might start taking notes about your baby’s behavior. You will be asked a series of questions at the checkup about your toddler’s behavior to look for autism signs. However, if you have any concerns before that make sure to contact your baby’s pediatrician to get help. 
  • Approval – You will realize very soon that your baby is now aware of your approval and disapproval. Learning positive behaviors can’t be done without this early step. Reward positive behavior and come up with consequences for bad behavior. 
  • Health –  Parents are always concerned about the health of their babies, which is perfectly normal. The most common illnesses that affect babies this age are diarrhea, vomiting, and constipation. Make sure to contact your doctor if you notice any symptoms of those as they can affect healthily reaching 21 month old milestones. 

Q: What should a 21 month old be saying?

A: Your little one is probably a little chatterbox by now. Learning new words will be a lot easier now than it was in previous months. You can expect two-word phrases such as “all done”, “let’s go”, and “mommy come” to start popping off soon. Don’t be surprised if you get a couple of simple questions either. 

Q: What should I expect from my 21 month old?

A: Toddlers this age are often interested in helping with chores, rearranging furniture, and copying what you’re doing in general. He might also wash and dry his hands, put on clothes on his own, and even brush his teeth with some help. You’re close to potty training so interest in the topic might also show up. 

Q: Should a 21 month old be talking?

A: Most 21 month olds use about 20-30 words every day, but they understand almost everything they hear. Babies this age are also able to use two-word phrases and even ask some simple questions. If your baby is having difficulties talking you might consider consulting with her pediatrician to make sure everything is fine. 

Q: How many body parts should a 21 month old know?

A: Naming at least 3 body parts is considered normal at this stage of development. Your baby will learn to name about 7-8 body parts until she turns 2.5 years of age. Still, babies understand what different body parts are meant for, they just don’t know how to name them. 

21 Month Old Food 

Eating is a very important part of your toddler’s life, but don’t make a huge deal about it. In simple words, don’t get into fights with your baby if she doesn’t want to eat those green beans and broccoli. Rather explain why they’re good and leave them on the table. Keep offering healthy options as much as you can. 

When it comes to eating schedule, stick to the one you’ve been using for a couple of months now: 3 meals and 2 snacks per day. Make sure you have a variety of foods available at any moment – fruits, vegetables, grains, dairy, and protein. 

All one-year-olds need fats for healthy brain development, that’s why you need to offer whole milk to your baby every day. Once your baby is 2 you can switch to skim or 1% milk. Doctors recommend 700mg of calcium per day for kids this age. Give your child 3 8-ounce cups of milk per day if that’s the only source of calcium. 

Weaning is also an important part for 21 month old development process. However, keep in mind that you need to go slow with it and drop one nursing session for at least 7 days before you drop another one. 

Q: How much milk does a 21 month old need?

A: About 3 8-ounce cups are considered a normal amount of whole milk for a 21 month old. This amount of milk is necessary for healthy brain development, but you can adjust it accordingly if there’s another source of calcium in your baby’s diet. Don’t offer more than this since too much milk can slow down processing other important ingredients. 

21 Month Old Sleep Schedule and Routine 


A healthy 21 month old development requires plenty of sleep. This will also help with your baby’s bad mood. Still, many parents have trouble with their baby’s sleep pattern and they need answers. 

You may have to deal with regression if your baby was a good sleeper before but is now giving you headaches since it started being more active. Illness, teething, or a holiday trip might impact your baby’s sleep routine and you will have a problem. 

It is not uncommon that babies resist bedtime at this age since everything else is more fun than sleeping. Still, your toddler needs to sleep to reach 21 month old milestones healthily. Make sure that your baby is being active enough during the day, that way you will get her easier to sleep. Turn off power devices at least an hour before putting her to bed, but you can leave noise machines on if she’s used to them. 

21 Month Old Activities

Make sure your baby stays active at all times. Get involved in activities with your baby for some fun bonding time and make sure you try some of these games and toys:

  • Tag – Running around and tagging you “it” is something that your baby is going to love!
  • Puzzle – About 50% of babies this age are interested in simple puzzles. 
  • Cardboard house – Cut out a hole in a large cardboard box and you will have a cheap and instant indoor playhouse for your little one. 

When Should You be Worried 

If you notice your baby is reaching certain milestones a bit slower than other toddlers don’t worry too much. Still, talk to your baby’s pediatrician if you notice these symptoms:

  • Uncontrollable tantrums
  • Clumsiness
  • Lack of empathy
  • Stiff head
  • Strange bumps 

My Babies Planet Overview 

Hopefully, your baby will reach all of these 21 month old milestones in time and in a healthy way. There will be some challenges regarding behavior and sleep, but you will eventually figure out how to deal with them. They’re a normal part of your baby’s development and you will get used to it. 

Hello Mother's and Father's of the world. My name is Sarah Nielsen is this is my passion MyBabiesPlanet.com, as I am a mother of two beautiful babies and they are my world. Also I love blogging and sharing my experiences of what has worked for me when raising my kids. When I'm not juggling the madness at home, or working on my blog. You will find me product researching and keeping the site freshly updated with the latest baby gear and helpful articles for my readers!