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Marks & Spencer
Here’s how Marks & Spencer fits your child compared to other brands you might be considering, so you know before it’s in your cart.
Find your child’s size in Marks & Spencer
Enter your child’s measurements once — we’ll size them in Marks & Spencer and at 100+ other brands, each from that brand’s own published chart. Height and weight are required; add chest, waist, hips and inseam to sharpen the fit.
Your child wears one size in Marks & Spencer. What should you buy elsewhere?
Pick the size your child wears at Marks & Spencer to see which brands have the same label and measurements (twins) and which run shorter or longer (strangers) — based on each brand’s own chart.
Show the full cross-brand table (every size)
| Marks & Spencer | Size twinssame number fits the same | Size strangerssame number, different cut |
|---|---|---|
| Prem Baby (3lbs)16.1" | — | No same-size match at other brands |
| Early Baby17.7" | — | No same-size match at other brands |
| Tiny18.9" | — | No same-size match at other brands |
| Newborn19.7" | Hanna Andersson↓ shorterPatagonia Kids↓ shorterBonpoint↓ shorterMacy's First Impressions↓ shorterMini Boden↓ shorterJoJo Maman Bébé↑ longer+1 more | |
| 121.3" | — | Mango Kids↑ longerLacoste Kids↑ longer |
| 1-324.4" | — | No same-size match at other brands |
| 3-627.2" | — | Primary↓ shorterMini Mioche↓ shorter |
| 6-928.4" | — | Primary↓ shorter |
| 9-1229.9" | — | Primary↓ shorter |
| 12-1832.7" | — | Primary↓ shorterMini Mioche↓ shorter |
| 18-2435.4" | — | Primary↓ shorter |
| 2-335.4–38.6" | ||
| 24-3638.6" | — | No same-size match at other brands |
| 3-438.6–40.9" | Uniqlo Kids↑ longer | |
| 4-540.9–43.3" | ||
| 5-643.3–45.7" | Uniqlo Kids↑ longer | |
| 6-745.7–48" | None — consistent across brands | |
| 7-848–50.4" | Uniqlo Kids↑ longer | |
| 8-950.4–52.8" | None — consistent across brands | |
| 9-1052.8–55.1" | None — consistent across brands | |
| 10-1155.1–57.5" | None — consistent across brands | |
| 11-1257.5–59.8" | None — consistent across brands | |
| 12-1359.8–62.2" | None — consistent across brands | |
| 13-1462.2–64.6" | None — consistent across brands | |
| 14-1564.6" | None — consistent across brands | |
| 15-1664.6" | Adidas Kids↑ longer |
Sizes shown use Marks & Spencer’s girls’/unisex chart where the brand splits by gender; boys’ sizes at the same number can run slightly taller.
In short
Where the number just works. At Prem Baby (3lbs), Early Baby, Tiny, 1-3, 24-36, 6-7 and more, Marks & Spencer lines up with every brand we track — the size carries straight over.
Where labels drift. The exceptions are the “strangers” above — e.g. at size 18-24, Primary cut the same number differently. Check those before you trust the label.
Bottom line: for most sizes, a Marks & Spencer number is a safe bet elsewhere — measure once, then double-check only the handful of “stranger” brands above.
Curious about a size that isn’t your child’s here? Every size, compared across every brand, lives here: Browse all size comparisons →
Fit & the transitions that trip parents up
Marks & Spencer-specific things the size number alone won’t tell you — drawn from its own charts.
Runs small — size up, especially school shirts
M&S uniform shirts come up noticeably smaller than Next at the same age, and some find the fit short-and-wide, which doesn't suit slim children. Sizing up is the common move.
British sizing by age
Labelled by age (converted from centimeters), so size to your child's height and measurements.
Specialty & inclusive fits
Which trimmer, roomier, or adaptive cuts Marks & Spencer publishes alongside its standard sizes.
What shoppers say about the fit
Community consensus
Shopper opinion · not Little & Youth’s measurementThis is what parents report anecdotally — crowd sentiment, not a Little & Youth determination. Our sizing above is computed from Marks & Spencer’s own published chart; the notes here come from public parent discussion.
Marks & Spencer kids runs small — parents routinely size up, especially on school shirts. The clearest signal is uniform: multiple parents find M&S school shirts come up noticeably smaller than Next in the same age, and some describe the fit as short-and-wide, which doesn’t suit slim children. Casualwear is a little less uniform — a stray dress or pinafore can run the other way — but the overall lean is that M&S runs small for the stated age. Sizing is British, by age/height.
Based on anecdotal discussion from multiple publicly available online sources; your experience may differ.
Should you buy Marks & Spencer?
Consider it if…
- You want solid school uniform — M&S is a British go-to for durable uniform basics.
- You want good-value quality — dependable fabric and construction for the price.
- You want classic, practical everyday pieces — not trend-driven.
Think twice if…
- You have a tall or slim child — the small, short-and-wide cut works against you; size up.
- You shop on Amazon — M&S sells through its own channels.
- You want statement fashion — it’s classic and practical by design.
Skip the cross-referencing — let Little & Youth do it.
Enter your child’s measurements once. We’ll show their Marks & Spencer size and their size at 100+ other brands, each from that brand’s own chart.
Find my child’s size →Shop Marks & Spencer ↗A few things parents ask that the chart won’t tell you
Do Marks & Spencer kids clothes run small?
Yes — the consistent parent read, strongest on school shirts, is that M&S comes up small for the age, noticeably smaller than Next. Sizing up is the common fix, particularly for tall or slim children.
How does M&S British age sizing work?
M&S sizes by age and height (ages 2–3 up to 15–16), which doesn’t map one-to-one to US numeric sizes. Our comparison lines it up against your child’s real height, and you can switch this page between inches and centimeters with the toggle above the table.
What measurements do I need to size Marks & Spencer accurately?
Marks & Spencer publishes height, weight, chest, waist, hip in its size chart. Height is the primary driver, and the chest/waist figures let you confirm body fit for a child between sizes.
Do Marks & Spencer boys’ and girls’ sizes fit the same?
From the bigger sizes up, Marks & Spencer publishes separate girls’ and boys’ charts, so the same number can differ by gender. The figures on this page use Marks & Spencer’s girls’/unisex chart.
Where do I buy Marks & Spencer?
Marks & Spencer is sold on its own site and through select retailers.