You’re reading a bedtime story and your kid asks for “thomething thweet” instead of “something sweet,” and it’s adorable, right up until the moment you start wondering if it’s supposed to sound like that by now.
So, what age should kids say the S sound? Most children say a clear S by about age 4¼, and nearly all by 5. A lisp or a “th” for “s” before then is very common. If S still sounds off after age 5, or the sound is “slushy,” a speech-language pathologist can help. You don’t have to wait to ask.
Typical ages for the S sound
These ages come from a review of studies of US English-speaking children. They show when about 90% of children say the sound clearly. Think of them as a guide, not a deadline.
| Age | What’s typical |
|---|---|
| 2–3 | S may be left off or swapped (“tun” for “sun”). Very common. |
| 3–4 | S shows up more often, with some “th” sounds mixed in. |
| 4–5 | Most children (90% by about 4¼) say S clearly in most words. |
| 5+ | If S still sounds off, it’s a good time to ask. |
Online, you’ll see ages for S from about 4 to 6, because studies draw the line in different places. We use the 90% mark from the best US review, which is about 4¼. Some children take a little longer.
What you might hear
S needs very precise tongue placement, which most toddlers haven’t built yet. While S is developing, you might hear:
- thun for sun, where the tongue pushes forward (often called a frontal lisp)
- tun for sun, or S left off the start of a word
- S missing in blends: top for stop, nake for snake
- A “slushy” or wet sound, where air slips out the sides of the tongue (a lateral lisp)
When to ask a speech-language pathologist
You don’t have to wait for a certain age to ask. If you’re wondering, ask. A speech-language pathologist (SLP) can tell you whether what you’re hearing is typical and what, if anything, to do next. Good reasons to check in:
- The S sounds “slushy” at any age (worth mentioning sooner, not later)
- S is still missing in blends like stop or snail after age 5
- Family, friends, or teachers often can’t understand your child
- Your child seems frustrated, or avoids talking
- You have any concern about hearing
Your pediatrician can point you to an SLP, and many public schools offer free screenings.
What to do tonight
- Say it back the natural way. If your child says “thun,” you say, “Yes! The sun is up!” No "say it again," no quiz.
- Read together. A few minutes, a few times a week, with a story that has lots of the sound.
- Make it a conversation. Ask about the pictures, add a little to what your child says, and ask again. ("What’s that?" "A truck." "Yes, a big red truck! Can you spot another one?") My mom put a research sheet on this, called dialogic reading, at the back of the original Chatter Batter books, and it still holds up.
- Keep it warm. A child who feels loved is more willing to keep trying.
The American Academy of Pediatrics recommends shared reading from birth through at least kindergarten, so there’s no wrong time to start.
Get it as an instant digital download and read it together tonight → The Secret City of Snails
This is exactly why we made The Secret City of Snails. It’s built around a secret phrase, “Simmery Simmery Soda Pop,” that turns the S sound into a game instead of a drill. In the story, Cindy the snail’s angel watches over a hidden city, and every S sound (whether it’s spelled with an s or a soft c) is highlighted right on the page, so the practice happens while you’re just reading together. It ends with a sing-along set to the tune of “Row, Row, Row Your Boat,” which our own kids have sung more times than I can count.
Not sure S is the sound to focus on yet? Take the free 60-Second Sound Check first. It’s not a screening, just a quick way to notice what your child is still growing into.
Frequently asked questions
Is a lisp normal for a 4-year-old?
Often, yes. Many 3- and 4-year-olds say “th” for “s.” A “slushy” sound where air comes out the sides is worth mentioning sooner.
At what age should S be clear?
About 90% of US children say S clearly by about 4¼. Some studies use a stricter bar and list later ages, up to 6.
Should I wait for my child to outgrow a lisp?
You don’t have to. If you’re wondering, a speech-language pathologist can tell you whether it’s likely to settle on its own or whether a little help would make it easier.
Read Next
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What Age Should Kids Say the TH Sound?
Working on more than one sound?
Chatter Batter started with my mom, Cindy Judd. She believed a child should feel loved, never tested, so she helped bring stories like these to life with the practice tucked inside. I’m Jed, a dad of seven, and I’ve been remastering these books so more families can read them together. One sound at a time, one story at a time.
This article is for general information, not a substitute for a speech-language evaluation. Every child grows at their own pace. If you’re wondering about your child’s speech or hearing, you don’t have to wait to ask your pediatrician or a speech-language pathologist.
Sources:
Crowe, K., & McLeod, S. (2020). Children’s English Consonant Acquisition in the United States: A Review. American Journal of Speech-Language Pathology, 29(4), 2155–2169. Ages in this article are when 90% of children say the sound clearly; the authors describe them as conservative.
American Speech-Language-Hearing Association. Speech Sound Disorders: Articulation and Phonology. Practice Portal.
American Academy of Pediatrics (2024). Literacy Promotion: An Essential Component of Primary Care Pediatric Practice.
Whitehurst, G. J. Dialogic reading. See the What Works Clearinghouse report.
A playful way to practice: Our free, ad-free kids’ arcade has a listening game called Sound Safari. Your child hears the “S” sound, then taps the bushes whose words have it. It’s a fun extra for home, not a replacement for speech therapy.
