For ages 4–7, most U.S. brands map a 4-year-old to size 4, ages 5–6 to size 5/6, and age 7 to size 7 or 7/8 — but height and body measurements decide the real fit.
A pajama that fits in one brand can hang off the shoulders in the next, which is why shopping by age alone often ends in a return. The size that fits a 4- to 7-year-old has to come from the brand’s chart plus a tape measure at home.
What Size Fits Ages 4–7?
Ages 4 through 7 usually fall into three size slots: 4, 5/6, and 7 or 7/8, depending on the brand.
Measure height first, then chest and waist, and compare against the specific brand’s chart before buying.
| Typical Age | Common Size | Reference Measurements |
|---|---|---|
| 4 years | 4 (XS) | Height under 42.5 in; chest 22 in; waist 21 in |
| 5–6 years | 5/6 (S) | Height under 46.25 in; chest 24 in; waist 22 in |
| 7 years | 7 or 7/8 | Height under 53 in; chest 27 in; waist 23.5 in |
| 4–5 years (metric chart) | 110 cm | 43.3 in height |
| 5–6 years (metric chart) | 116 cm | 45.7 in height |
| 6–7 years (metric chart) | 122 cm | 48.0 in height |
How The CPSC Sleepwear Rules Affect Sizing
Under 16 C.F.R. part 1615, the rules cover sizes above 9 months up to 6X; under 16 C.F.R. part 1616, sizes 7 through 14. Sleepwear is regulated up to size 14, so pajamas for a 4-to-7-year-old sit inside federal safety rules. Covered garments include nightgowns, pajamas, robes, and loungewear intended primarily for sleeping. The rules trace back to burn injuries from ignition sources like matches, lighters, candles, ranges, stoves, space heaters, and fireplaces.
Tight-fitting sleepwear is handled differently from loose-fitting sleepwear, with separate maximum-dimension tables. CPSC guidance says tight-fitting sleepwear sizes must be expressed as months or numbers — not XS, S, M, L, or XL. If you see a sleepwear set labeled only “Small,” treat that as a loose-fitting signal and check the fit chart.
Where Age-Based Shopping Goes Wrong
Age is not the sizing standard — measurements are. Every fit input on a retailer chart is physical: height, chest, waist, hip, and inseam. The size number isn’t universal either: one brand’s 7/8 can fit a child who wears a 7 in another because cut patterns differ. Two traps:
- Assuming size 7 means the same everywhere — some brands use 7, others 7/8.
- Ignoring the tight-versus-loose distinction, which changes regulatory treatment and drape.
Because brands cut differently, sizing up “just in case” often backfires on sleepwear: a loose fit on a tight-fitting garment defeats the design, and an oversized garment can ride up during sleep. This roundup of 4-7 years pyjamas covers options that fit this age band. The CPSC’s own children’s sleepwear FAQ spells out the size and safety rules in full.
The honest guide: measure your child’s height and chest, open the specific brand’s chart, and match those numbers to the size band — not the age band.
FAQs
Should I size up or down for children’s pajamas?
Match the brand’s chart rather than sizing up by default. Height and chest measurements are the reliable inputs, and sizing up on a tight-fitting sleepwear garment can defeat the design and cause it to ride up. Only size up when your child’s measurements land between two bands on that brand’s chart.
Is size 7 the same as 7/8?
No — it depends on the brand. Some manufacturers cut to a straight 7, others use a 7/8 combined size. Always check the retailer’s chart, because a 7/8 in one brand may fit a child who wears a 7 in another.
Why don’t children’s pajama sizes use S, M, and L?
CPSC guidance says tight-fitting sleepwear sizes must be expressed as months or numbers, not XS, S, M, L, or XL. A numeric size label signals how the garment is classified and regulated, and gives a more precise fit reference than a generic letter size.
References & Sources
- U.S. Consumer Product Safety Commission. “Children’s Sleepwear FAQ” Explains the size range, tight-fitting labeling rules, and the ignition sources behind the regulations.
- U.S. Consumer Product Safety Commission. “Summary Fact Sheet: Children’s Sleepwear” Covers the 16 C.F.R. part 1615 and part 1616 coverage split by size.
- U.S. Consumer Product Safety Commission. “Children’s Sleepwear Lab Bulletin” Details the testing and certification requirements for sleepwear garments.