Tiny Milestones guides

When do babies roll, sit, crawl, and walk?

By the CDC's checklists, most babies roll from tummy to back by 6 months and sit without support by 9 months. Hands-and-knees crawling is common but not universal: in the WHO's study of healthy children it began anywhere from about 5 to 13 months, and a few babies never crawled that way. First steps alone came between about 8 and 18 months in the same study, and the CDC puts a few steps on its 15-month checklist. The two sources measure different things, which is why their numbers look different.

Two kinds of numbers

Most ages you see quoted for motor milestones come from one of two public sources, and they don't mean the same thing.

A CDC checkpoint is the age by which at least 75 percent of children are expected to show a skill. The CDC's 2022 checklists place each milestone at a well-child visit age, from a 2019 review of published studies plus the authors' clinical judgment¹. The CDC chose 75 percent instead of the average age on purpose: at the average, half of all children would not have the skill yet, so a missing milestone is easy to wave off with "wait and see"¹. A CDC age is a "most babies by" point, not an average and not a deadline, and the CDC says its checklists are not standards and not screening or diagnostic tools¹.

A WHO window comes from the WHO Multicentre Growth Reference Study, which followed 816 healthy children in Ghana, India, Norway, Oman, and the United States from 4 to 24 months. Trained observers checked each child against a written definition of six gross motor skills, and the ages were published as percentiles from the 1st to the 99th². The span from the 1st to the 99th percentile is what the WHO calls the window of achievement, and it draws no "late" line inside it²³.

Rolling

Rolling from tummy to back is on the CDC's 6-month checklist⁴. The American Academy of Pediatrics notes that term babies often roll from stomach to back around 4 months⁵, so 6 months is the "most babies by" point, not the usual age. The CDC's 2022 checklists don't list rolling from back to tummy; the AAP's own milestone list puts it at about 6 months⁶. The WHO study didn't measure rolling.

Sitting

Sitting without support is on the CDC's 9-month checklist, along with getting into a sitting position alone⁷; leaning on hands to sit is on the 6-month list⁴. In the WHO study, sitting without support (upright, head steady, for at least 10 seconds, no hands) was reached between 3.8 and 9.2 months, with half of children sitting by about 6 months². The top of the WHO window and the CDC checkpoint land on the same month, 9, which is reassuring: two methods, one answer.

Crawling

In the WHO study, crawling on hands and knees began between 5.2 and 13.5 months, with half of children crawling by about 8 months. About 4 in every 100 of these healthy children never crawled on hands and knees at all², which is why crawling makes a poor test. The CDC's 2022 checklists don't list crawling⁷⁸. If your baby scoots, rolls, or goes straight to pulling up, that is one of the ordinary routes.

Standing and cruising

The CDC's 1-year checklist has pulling up to stand and walking while holding on to furniture⁸. In the WHO study, standing while holding on ran from 4.8 to 11.4 months, walking with support from 5.9 to 13.7 months, and standing alone from 6.9 to 16.9 months². The WHO window for walking with support brackets the CDC's 1-year point.

Walking

Walking alone, defined in the WHO study as at least five steps with no support, was reached between 8.2 and 17.6 months, with half of children walking by about 12 months and 19 in 20 by about 15 months². The CDC's 15-month checklist says "takes a few steps on his own," and the 18-month list has walking without holding on to anyone or anything⁹¹⁰. So a baby who walks at 10 months and one who walks at 16 months are both inside the window.

The order is not fixed, and sex makes no difference

About 90 percent of the WHO's children reached five of the six skills in the same order, and the rest didn't². The WHO also checked whether boys and girls reach these skills at different ages and found no consistent difference, so it publishes one set of windows for both¹¹.

Born early?

For a baby born more than 3 weeks early, pediatricians count age from the due date for the first 2 years⁵⁶. Our guide to adjusted age shows how to work it out.

When to talk with your pediatrician

The CDC's advice is simple: you know your child best, and you don't have to wait for a checkup. If your baby isn't meeting one or more milestones, has lost a skill they once had, or you're worried for any reason, talk with your child's doctor, share what you've noticed, and ask about developmental screening¹². If you or the doctor are still concerned, ask for a referral to a specialist, and call your state's early intervention program; its services are free or at reduced cost for children who qualify¹²¹³.

The CDC's milestone checklists are free at cdc.gov. Our summary of them implies no endorsement by the CDC, HHS, or the U.S. Government.

This is general information, not medical advice. Ask your baby's doctor about your own baby.