The First 1,096 Days

Birth to age three

The first 1,096 days

When to expect the first smile, the first roll, the first steps and the first “why?”, with the real ranges behind each one. Every baby takes a different route along this path.

Enter a birthday to mark your baby’s age across the whole page. It stays in this browser tab and isn’t saved or sent anywhere.

At a glance

When to expect the big ones

Bars show the range measured in healthy children. A diamond marks the age the CDC checks for, when at least 75% of children have the skill. Select a row to jump to that age.

View this chart as a table

Why the ages differ

Why one site says 12 months and another says 18

“Walks by 12 months” is usually an average: half of babies have done it by then. “Walks by 18 months” is a check-in age: nearly all have, so it’s a good moment to ask if your child hasn’t.

Both are true. In 2022 the CDC moved its checklists from average ages to ages when at least 75% of children have the skill, which is why some milestones appear later than in older guides.

View the WHO percentiles as a table

The timeline

Stop by stop

Each stop matches a well-child visit age on the CDC’s checklists, and each list shows what at least 75% of children do by that age. Stops aren’t evenly spaced in time.

Talking, in one thread

From “aahh” to “why?”

Talking starts long before words. Sounds become babble, babble becomes names, and names become a toddler asking questions at breakfast.

The sample lines come from the CDC’s own examples. The ages are “most children by”, so plenty of children get there sooner.

The AAP notes “tremendous variance” in when recognizable words appear, and that boys generally start talking later than girls. Hearing is worth raising with your doctor if speech worries you.

    If something feels off

    Don’t wait and see

    The CDC’s message is simple: act early. A missed milestone isn’t a diagnosis, but it is a reason to ask.

    Lost skills

    If your child has lost a skill they once had, tell their doctor. This is on the CDC’s list of reasons to act at every age.

    Talk to the doctor

    Share what you’ve noticed and ask about developmental screening. You don’t need to wait for the next checkup.

    Still concerned?

    Ask for a referral to a specialist. Under age 3, you can also contact your local early intervention system for a free evaluation, and you don’t need a referral or diagnosis to call. From age 3, call any local public elementary school.

    Born early?

    Subtract the weeks born early from your baby’s age, and use that adjusted age until age 2. The AAP notes most children have caught up to the typical range by then.

    Screenings the AAP recommends for every child

    These ages and checklists support conversations with your doctor. The CDC says its milestones are not developmental standards and are not screening or diagnostic tools. This page is general information, not medical advice.

    Where this comes from

    Sources

    All pages checked October 30, 2026. Checklist wording is lightly adapted from the CDC, mainly to replace “he” and “she”.

    ↑ ↓ to move, Enter to jump, Esc to close. On the page, J and K step through ages.