SIIX Collection
Santa Baby Long Sleeve Romper
Santa Baby Long Sleeve Romper
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One less thing to stress about this holiday season! This cozy Santa Baby romper is made from the softest organic cotton and works for everyday errands, lunch dates, or meeting all the cousins for the first time.
- Material: 100% organic cotton
- Care: Machine wash cold, hang to dry
- Sizes: 3-6M to 18-24M

Size Guide
Not sure which size to pick? Use the charts below as a starting point. Sizes can vary a little from brand to brand, so check the product description for any fit notes, and when in doubt, size up. Little ones grow fast!
Still unsure? Call or stop by the shop at 112 S 9th St in Mt. Vernon, IL, and we'll help you choose. Local pickup is always free, and we ship anywhere in the U.S. for $7.99 (free on orders of $75+).
How to measure
- Height: Measure standing (or lying flat for babies) from the top of the head to the heels, without shoes.
- Weight: Use your child's most recent weight. If height and weight point to different sizes, go by height.
Baby sizes
| Size | Height | Weight |
|---|---|---|
| Newborn | 18 to 21.5 in | 6 to 9 lbs |
| 0-3M | up to 24 in | up to 12.5 lbs |
| 3-6M | 24 to 27 in | 12.5 to 17 lbs |
| 6-9M | 27 to 28.5 in | 17 to 21 lbs |
| 9-12M | 28.5 to 30 in | 21 to 25 lbs |
| 6-12M | 27 to 30 in | 17 to 25 lbs |
| 12-18M | 30 to 32 in | 25 to 28 lbs |
| 18-24M | 32 to 34 in | 28 to 30 lbs |
Toddler sizes
| Size | Height | Weight |
|---|---|---|
| 2T | 35 to 36.5 in | 29 to 31 lbs |
| 3T | 36.5 to 39 in | 31 to 33 lbs |
| 4T | 39 to 41.5 in | 34 to 37.5 lbs |
| 5T | 41.5 to 44 in | 37.5 to 42 lbs |
Kids sizes
| Size | Height | Weight |
|---|---|---|
| 4 | 40 to 42.5 in | 34 to 38.5 lbs |
| 5 or 4/5 | 42.5 to 45 in | 38.5 to 43 lbs |
| 6 or 5/6 | 45 to 47.5 in | 43 to 48 lbs |
| 7 | 48 to 51.5 in | 50 to 59.5 lbs |
| 8 | 50.5 to 53.5 in | 59.5 to 69.5 lbs |
These charts are a general guide based on common US children's sizing. Youth sizes (S, M, L) and big-kid sizes like 10 to 14 vary more by brand, so check the product page or ask us.
Brand fit notes
- Elevated Faith and Smiley Daze oversized tees: Made with a roomy, oversized fit. Choose your usual size for a relaxed look.
- Bamboo pajamas and zip sleepers (The Cozy Munchkin, Little One Shop): Made to fit snug for sleepwear safety. Don't size up for extra room.
- Knotted gowns (Three Little Tots): Fit newborn to 3 months, about 5 to 15 lbs.
- Little Stocking Co tights: Choose your child's clothing size. If they're between sizes, size down.
- Everything else: Most of our brands fit true to size. Any brand-specific notes are listed in the product description.
Ordered the wrong size? See our Refund Policy.