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Baby sizing, brand by brand · Little & Youth

What size is 12–18M?How a 12–18M compares across 27 baby brands — by weight

A 12–18M isn't the same everywhere. Baby sizes are set mostly by weight, and each brand draws its 12–18M a little differently. Here is every brand on Little & Youth that sells a 12–18M, then the brands that call the same weight something else.

The short answer: At the 27 brands on Little & Youth that sell a size called 12–18M, it fits a baby of about 23–27 lb, roughly 30–32 in long — the middle of those brands' own published ranges. Baby sizes are set mostly by weight, then length, so weigh before you buy. Across those brands the same 12–18M spans 20–30 lb. 24 more brands sell a size with a different name whose own published weight overlaps this range; they're listed separately, exactly as each brand prints them.

Brands that sell a size called 12–18M

Each brand's own published weight and length for its 12–18M, lightest to heaviest. Expand "source" for the chart each row comes from.

12–18M across 27 brands — weight (lb) and length (in), as each brand publishes them.
BrandTheir sizeWeightLength
Hanna Andersson12-18M (75 cm)20–24 lb28–30 in
source
Chart: Baby & Toddler · Source: https://www.hannaandersson.com/kids-size-chart.html · Captured: 2026-09-04
Old Navy12-18M21–24 lb29–31.5 in
source
Chart: Baby · Source: https://oldnavy.gap.com/browse/product.do?pid=614457002 · Captured: 2026-09-20
Uniqlo Kids12-18 months(80)24.3 lb29.53–33.46 in
source
Chart: BABY Nude Dimensions · Source: https://www.uniqlo.com/us/en/size/dimension_kids.html · Captured: 2026-09-04
Kyte Baby12-18M22–25 lb29–31 in
source
Chart: Infant & Toddler apparel (weight+height) · Source: https://kytebaby.com/pages/sizing-chart · Captured: 2026-09-30
L.L. Bean Kids12-18 Months22–25 lb29–32 in
source
Chart: Kids Sizing - Infants · Source: https://www.llbean.com/llb/shop/518113?page=sizing-charts · Captured: 2026-09-04
JoJo Maman Bébé12-18 mths25.4 lb33.86 in
source
Chart: Baby 0 - 24 Months · Source: https://www.jojomamanbebe.com/us/en/sizing-and-care-guide/baby-and-childrens-size-guide · Captured: 2026-09-04
Little Sleepies12-18m23–26 lb31–33 in
source
Source: https://littlesleepies.com/pages/sizing-guide · Captured: 2026-10-07
Quincy Mae12-18m22–26 lb30–33 in
source
Chart: Quincy Mae — Body · Source: https://ryleecru.customerdesk.io/#rp-customer-widget-faq-ebe725ad-f773-4634-bbd6-0c8dd0af7e18 · Captured: 2026-09-13
Rylee + Cru12-18m22–26 lb30–33 in
source
Chart: Rylee + Cru — Body (Baby + Kids) · Source: https://ryleecru.customerdesk.io/#rp-customer-widget-faq-ebe725ad-f773-4634-bbd6-0c8dd0af7e18 · Captured: 2026-09-13
Mini Boden12-18Mup to 26.5 lbup to 34 in
source
Chart: GIRLS & BOYS BODY MEASUREMENTS · Source: https://global.boden.com/pages/childrens-size-and-fit-chart · Captured: 2026-09-04
babyGap12 - 18 mos22–27 lb29–31 in
source
Chart: BABY SIZE CHART · Source: https://www.gap.com/customer-service/size-charts?cid=2105 · Captured: 2026-09-04
Hatley12-18m25–27 lb29.25–31 in
source
Chart: Baby · Source: https://us.hatley.com/pages/size-chart · Captured: 2026-10-05
Janie and Jack12 - 18 m girls22–27 lb29–31 in
source
Chart: Baby Girl - Clothing · Source: https://www.janieandjack.com/janieandjack-size-charts.html?lang=en_US · Captured: 2026-09-04
Janie and Jack12 - 18 m boys22–27 lb29–31 in
source
Chart: Baby Boy - Clothing · Source: https://www.janieandjack.com/janieandjack-size-charts.html?lang=en_US · Captured: 2026-09-04
Janie and Jack12 - 18 m22–27 lb29–31 in
source
Chart: Baby - Clothing · Source: https://www.janieandjack.com/janieandjack-size-charts.html?lang=en_US · Captured: 2026-09-04
Magnetic Me12-18M22–27 lb30.5–32 in
source
Chart: Baby · Source: https://www.magneticme.com/pages/size-chart · Captured: 2026-09-04
Monica + Andy12-18M24–27 lb30–31 in
source
Chart: Baby Sizes · Source: https://monicaandandy.com/products/oversized-slouchy-tee · Captured: 2026-10-05
Tea Collection12-18M22–27 lb30.5–33 in
source
Chart: Baby 0-3m To 18-24m (only the rows not already in 'Newborn Nb To 6-12m') · Source: https://teacollection.com/pages/size-chart · Captured: 2026-09-09
Primark Kids12-18 months27.6 lb31.5–33.86 in
source
Chart: Baby Clothes: Newborn - 36 Months (product-page Size Guide) · Source: https://www.primark.com/en-us/p/0-18mths-disney-pixars-toy-story-newborn-romper-ivory-991181820006 · Captured: 2026-10-07
Columbia Kids12-18M28 lb32 in
source
Chart: Infant · Source: https://www.columbia.com/t/size-fit/ · Captured: 2026-09-19
Gymboree12-18M26–28 lb30.5–33 in
source
Chart: Baby · Source: https://www.gymboree.com/us/content/size-chart · Captured: 2026-10-07
Hudson Baby12-18M26–28 lb30.5–32 in
source
Chart: Children's Pajamas · Source: https://hudsonchildrenswear.com/pages/sizechart.html · Captured: 2026-10-05
J.Crew Crewcuts12 - 18 M26–28 lb30.5–32 in
source
Chart: Baby (Height/Weight/Waist/Chest; no metric table published) · Source: https://www.jcrew.com/r/size-charts · Captured: 2026-09-04
Patagonia Kids12-18M25–28 lb31–33 in
source
Chart: Infants & Toddlers Size Chart · Source: https://www.patagonia.com/size-unisex-infant-data.html?format=ajax · Captured: 2026-09-04
The Children's Place12-18M26–28 lb30.5–33 in
source
Source: https://www.childrensplace.com/us/content/size-chart · Captured: 2026-10-07
The North Face Kids12M-18M25–30 lb31–33 in
source
Chart: Baby Apparel · Source: https://www.thenorthface.com/en-us/help/size-charts · Captured: 2026-09-09
Joules Kids12-18m—31.5–34 in
source
Chart: BABY & TODDLER · Source: https://joulesuk.zendesk.com/hc/en-gb/articles/30459306847505-Size-Guides · Captured: 2026-09-04
Mango Kids12-18 months—33.86 in
source
Chart: Newborn — full body ladder (as published under "Pajamas") · Source: https://shop.mango.com/us/en/size-guide · Captured: 2026-09-20
Mango Kids12-18 months girls—33.86 in
source
Chart: Baby girl — full body ladder (as published under "Dresses and jumpsuits") [4 years / 5-6 years omitted - identical rows live on the Girl/Boy chart] · Source: https://shop.mango.com/us/en/size-guide · Captured: 2026-09-20
Mango Kids12-18 months boys—33.86 in
source
Chart: Baby boy — full body ladder (as published under "Sweatshirts") [4 years / 5-6 years omitted - identical rows live on the Girl/Boy chart] · Source: https://shop.mango.com/us/en/size-guide · Captured: 2026-09-20
Zara Kids12-18 months—up to 33.86 in
source
Chart: Baby · Source: https://www.zara.com/us/en/textured-floral-print-bodysuit-p05767587.html · Captured: 2026-09-20

Same weight, different label

These brands don't sell a size called 12–18M. Each row is one of the brand's own sizes whose published weight overlaps 23–27 lb — shown with the brand's label, weight and length as printed. Labels are the brands' own; we don't treat them as the same size as 12–18M.

Other baby sizes whose own published weight overlaps the 12–18M weight band.
BrandTheir sizeWeightLength
abercrombie kids12 mos21–25 lb29–31 in
source
Chart: Baby & Toddler · Source: https://www.abercrombie.com/shop/us/kids/p/straight-jeans-56562026 · Captured: 2026-09-04
Burt's Bees Baby12M21–25 lb28.5–30.5 in
source
Chart: Baby/Toddler/Kids · Source: https://www.burtsbeesbaby.com/pages/baby-clothes-size-chart · Captured: 2026-09-04
Carter's12M21–25 lb28.5–30 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 21–24.5 lb, 28–30 in
Converse Kids12 Months22.5–25 lb29–31.5 in
source
Chart: Infant & Toddler Apparel · Source: https://www.converse.com/size-chart-guide?id=infantandtoddler-tops&modal=false · Captured: 2026-09-09
Jacadi18M22–25 lb32 in
source
Chart: Baby · Source: https://www.jacadi.us/size-chart · Captured: 2026-09-20
Little Planet by Carter's12M21–25 lb28.5–30 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 21–24.5 lb, 28–30 in
Macy's Epic Threads12M22–25 lb28–30 in
source
Source: https://www.macys.com/xapi/digital/v1/product/18446918/sizechart/241466560?clientId=PROS · Captured: 2026-09-09
Macy's First Impressions12M22–25 lb28–30 in
source
Chart: Baby · Source: https://www.macys.com/xapi/digital/v1/product/21640640/sizechart/267301644?clientId=PROS · Captured: 2026-09-20
OshKosh B'gosh12M21–25 lb28.5–30 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 21–24.5 lb, 28–30 in
Otter Avenue12M21–25 lb28.5–30 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 21–24.5 lb, 28–30 in
Polo Ralph Lauren Kids12M22.5–25 lb29.5–31 in
source
Chart: Baby Size Guide - Apparel · Source: https://www.ralphlauren.com/baby-size-guide/baby_all_ages_apparel.html · Captured: 2026-09-09
Calvin Klein Kids18 Months girls22–26 lb30–32 in
source
Chart: Infant Girls · Source: https://www.calvinklein.us/en/kids-size-guide.html · Captured: 2026-09-09
Calvin Klein Kids18 Months boys22–26 lb30–32 in
source
Chart: Infant Boys · Source: https://www.calvinklein.us/en/kids-size-guide.html · Captured: 2026-09-09
Cloud Island18M23.5–26 lb31–32.5 in
source
Chart: Baby · Source: https://digitalcontent.target.com/itemcontent/sizecharts/htmlfragments/baby-toddler-clothing/cloud-island/regular.html · Captured: 2026-10-05
Garanimals18M22.5–26 lb30–31.5 in
source
Source: https://www.garanimals.com/size-chart · Captured: 2026-09-04
Target Cat & Jack18M23.5–26 lb31–32.5 in
source
Chart: Baby · Source: https://digitalcontent.target.com/itemcontent/sizecharts/htmlfragments/baby-toddler-clothing/cat-jack/regular.html · Captured: 2026-09-20
Target Cat & Jack18M girls23.5–26 lb31–32.5 in
source
Chart: Toddler Girls · Source: https://digitalcontent.target.com/itemcontent/sizecharts/htmlfragments/baby-toddler-clothing/cat-jack/toddler-girls.html · Captured: 2026-09-04
Target Cat & Jack18M boys23.5–26 lb31–32.5 in
source
Chart: Toddler Boys · Source: https://digitalcontent.target.com/itemcontent/sizecharts/htmlfragments/baby-toddler-clothing/cat-jack/regular.html · Captured: 2026-09-20
Under Armour Kids18M22–26 lb30.5–33 in
source
Chart: Infant · Source: https://www.underarmour.com/en-us/t/size-guide/boys-tops/ · Captured: 2026-09-20
Walmart Wonder Nation18M22.5–26 lb30–31.5 in
source
Source: https://www.walmart.com/ip/Wonder-Nation-Boys-Kid-Tough-T-Shirt-Sizes-XS-XXL-and-Husky/938545778 · Captured: 2026-09-20
Amazon Essentials Kids18M24–26.5 lb31–32.5 in
source
Source: https://z-ecx.images-amazon.com/images/G/01/apparel/en_US/html/sizechart/kids._V201566742_.html · Captured: 2026-09-20
Macy's Epic Threads18M25–27 lb31–33 in
source
Source: https://www.macys.com/xapi/digital/v1/product/18446918/sizechart/241466560?clientId=PROS · Captured: 2026-09-09
Macy's First Impressions18M25–27 lb31–33 in
source
Chart: Baby · Source: https://www.macys.com/xapi/digital/v1/product/21640640/sizechart/267301644?clientId=PROS · Captured: 2026-09-20
Primary12-1822–27 lb29–31 in
source
Chart: All Baby Clothing (rows 2 and 3 omitted - see notes.md) · Source: https://size-chart-server.primary.codes/all-baby-clothing · Captured: 2026-09-09
Guess18M24.5–27.5 lb31–32.5 in
source
Source: https://content.guess.com/GuessUS/Frontend/sizechart/kids_sizecharts.html · Captured: 2026-09-04
Levi's Kids18M24.5–27.5 lb30.5–32.5 in
source
Chart: Kids Baby - INFANT · Source: https://www.levi.com/US/en_US/info/sizeguide · Captured: 2026-09-04
Polo Ralph Lauren Kids18M25.5–27.5 lb31.5–33 in
source
Chart: Baby Size Guide - Apparel · Source: https://www.ralphlauren.com/baby-size-guide/baby_all_ages_apparel.html · Captured: 2026-09-09
abercrombie kids18 mos25–28 lb31–34 in
source
Chart: Baby & Toddler · Source: https://www.abercrombie.com/shop/us/kids/p/straight-jeans-56562026 · Captured: 2026-09-04
BoxLunch18 Months24–28 lb—
source
Chart: Infant/Baby · Source: https://www.boxlunch.com/customer-service/merchandise/size-fit-guide/ · Captured: 2026-09-04
Burt's Bees Baby18M25–28 lb30.5–32.5 in
source
Chart: Baby/Toddler/Kids · Source: https://www.burtsbeesbaby.com/pages/baby-clothes-size-chart · Captured: 2026-09-04
Carter's18M25–28 lb30–32 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 24.5–27 lb, 30–32 in
Converse Kids18 Months25.5–28 lb31.5–34 in
source
Chart: Infant & Toddler Apparel · Source: https://www.converse.com/size-chart-guide?id=infantandtoddler-tops&modal=false · Captured: 2026-09-09
Gerber Childrenswear18M24–28 lb30–32 in
source
Chart: Preemie to Toddler · Source: https://www.gerberchildrenswear.com/pages/size-chart-gerber-childrenswear · Captured: 2026-09-04
Cotton Pajamas chart, same size: 20–24 lb, 30–33 in
Jacadi24M25–28 lb35 in
source
Chart: Baby · Source: https://www.jacadi.us/size-chart · Captured: 2026-09-20
Little Planet by Carter's18M25–28 lb30–32 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 24.5–27 lb, 30–32 in
Noralee12m22–28 lb30–33 in
source
Chart: Noralee — Body · Source: https://ryleecru.customerdesk.io/#rp-customer-widget-faq-ebe725ad-f773-4634-bbd6-0c8dd0af7e18 · Captured: 2026-09-13
OshKosh B'gosh18M25–28 lb30–32 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 24.5–27 lb, 30–32 in
Otter Avenue18M25–28 lb30–32 in
source
Chart: Pajamas (general body ladder) · Source: https://www.carters.com/size-chart · Captured: 2026-10-07
Outerwear chart, same size: 24.5–27 lb, 30–32 in

Weight, length and the diaper

Two babies of the same age can be two sizes apart, which is why the age on the tag is the weakest guide. Go by weight first, then length. Bodysuits and footed sleepers also have to close over a diaper: if your baby is near the top of a brand's range, is long for their weight, or wears cloth diapers, the next size up usually snaps more easily.

Common questions about 12–18 months sizes

What weight is a 12–18M for?

At the 27 brands on Little & Youth that sell a 12–18M, it fits a baby of about 23–27 lb — the middle of their own published ranges. Brands vary: the same 12–18M spans 20–30 lb across them, so check the brand's own weight range.

Is a 12–18M the same at every brand?

No. Baby sizes aren't standardized — across the brands here a 12–18M covers 20–30 lb, and some brands name the same weight differently (a single age like 6M, months like 6 mos, or a centimetre size). Weigh and measure your baby and compare against each brand's own chart.

Know your baby's size at every brand. Let Little & Youth do it.

Enter your baby's weight and length once and Little & Youth shows the size to buy across the brands on the site — each from that brand's own published chart.

Find your child's size →
Their Measurements. Right Size. Brand by Brand.
How we know this is accurate. Every weight and length on this page is transcribed from that brand's own published baby size chart — no estimates and no averaged-out "standard". Where a brand prints only an upper limit ("up to 7 lb"), that is how it is shown. Brands update their charts, so confirm against the brand's live chart before you buy. Little & Youth is independent and not affiliated with any brand listed. Figures verified 2026-10-08.