Cat & Jack Baby Size Chart — Fit by Weight & Height
The Cat & Jack baby-clothing size chart, size by size — the weight and height each label covers, and how Cat & Jack compares with the median of the 30 brands in our Size Index. Based on the brand’s own published chart (retrieved 2026-09-02); we compare published charts and do not handle or test any garment.
Across its published chart, each Cat & Jack size covers about 1.0 lb less than the 30-brand median, averaged across 12 sizes in our Size Index. If your baby is near the top of a weight range, size up in Cat & Jack.
Cat & Jack baby size chart (weight & height)
| Size | Fits weight | Height | 30-brand median | Cat & Jack vs median |
|---|---|---|---|---|
| Preemie | up to 5.5 lb | up to 17.5 in | 5.5 lb | 0 |
| Newborn | 6–8 lb | 18–20 in | 8 lb | 0 |
| 0-3M | 9–12 lb | 20.5–23.5 in | 12 lb | 0 |
| 3-6M | 12.5–16 lb | 24–25.5 in | 17 lb | −1 lb |
| 6-9M | 16.5–19.5 lb | 26–27.5 in | 20 lb | −0.5 lb |
| 12M | 20–23 lb | 28–30.5 in | 24 lb | −1 lb |
| 18M | 23.5–26 lb | 31–32.5 in | 27 lb | −1 lb |
| 24M | 26.5–28 lb | 33–35.5 in | 30 lb | −2 lb |
| 2T | 26.5–28 lb | 33–35.5 in | 31 lb | −3 lb |
| 3T | 28.5–32 lb | 36–38.5 in | 34 lb | −2 lb |
| 4T/4 | 32.5–37 lb | 39–43 in | — | — |
| 5T/4 | 37.5–42 lb | 43.5–44.5 in | — | — |
Read the “vs median” column to see where Cat & Jack differs: a positive number means that size covers heavier babies than the typical brand (runs bigger on paper); negative means smaller. Compared across 10 matching sizes; our Size Index also counts the 4T/4 and 5T/4 rows (as 4T and 5T), so the average above covers 12 sizes.
How we built this
There is no US standard for baby-clothing sizes, so the same label fits different weights at different brands. This page reproduces the Cat & Jack published size chart and compares each size to the median of 30 brands from our Baby Clothing Size Index 2026. Figures are from the brand’s published chart (retrieved 2026-09-02); we compare published charts only and never claim to have measured or tested a garment. For clothing fit only — not a guide to how much a baby should weigh.