How do I measure baby length at home for clothes size?

Do I measure the baby or the sleepsuit?

Measure the baby. John Lewis and Mamas & Papas both say their charts are body measurements, not the measurement of the garments. Next's children's measurement guide is written the same way: measure the body, then pick the size. C&A's baby chart uses body length in centimetres (size 56 means up to about 56cm long). A tape run along a hanging babygrow tells you nothing those charts can use.

How do I take a crown-to-heel length at home?

You need a second pair of hands if you can get one, a soft tape or a rigid ruler, and a flat surface. C&A describes the shopping method as: baby lying flat, measure from the crown of the head to the heel, legs gently straightened. That is body length for a clothes chart, not a clinic board.

1. 1
   Lie baby on a firm flat surface A changing mat on the floor, or the middle of a bed with a hand on baby the whole time. RoSPA's fall advice is never to leave a baby on a raised surface.
2. 2
   Line the head up The crown (top of the head, not the forehead) touches a book, skirting, or the zero end of the tape. Keep the head still; do not crush the neck.
3. 3
   Straighten the legs gently One adult holds the head. The other brings both legs down so the knees are as straight as baby will allow and the tape reaches the heel, not the toes.
4. 4
   Read centimetres, write the date Use the figure the same day you order. Growth in the first months is fast enough that a six-week-old measurement is already stale for an online 0–3 pack.
5. 5
   If the chart also wants chest or hip C&A: chest at the fullest part just under the arms; hip around the widest part, leaving room for the nappy. Skip these if the UK chart only lists height and weight.

A wriggly baby will not give a millimetre-perfect number. For shopping, a figure to the nearest centimetre is enough to choose between 50cm, 56cm and 62cm bands.

Is a home tape the same as the length in the red book?

No. RCPCH says that up to two years, length is taken on a length board or mat, shoes and nappy removed, by people who are trained or supervised. The Child Growth Foundation parent guide says infants under two should be measured lying down by a trained professional with specific equipment if the figure is for growth. A home tape for a Next order is a shopping shortcut. Do not plot it on the UK-WHO chart or decide a baby has "dropped a centile" from the changing-mat number.

Clinic length in the red book is also occasional. Reviews do not always include a new length. That is why parents still need a home cm before clicking 0–3 online.

Which clothes band does my centimetre figure point to?

Open the brand chart. Examples checked 10 September 2026: Next First Size 50cm, Up to 1 month 56cm, Up to 3 months 56–62cm; John Lewis Newborn up to 56cm, 0–3 months 56–62cm; Mamas & Papas Newborn 50cm, up to 1 month 56cm, 0–3 months 62cm; C&A size 56 is 51–56cm body length, size 62 is 57–62cm. If the measurement sits on a boundary, the larger band is the one that still fits next week.

• Under 50cm — First Size / Newborn / size 50 on charts that start there; Tiny Baby if weight also matches.
• 50–56cm — John Lewis Newborn or Next Up to 1 month, depending on weight as well.
• 56–62cm — 0–3 months on John Lewis and Next; C&A 62.
• Weight still wins on some labels — a short, heavier baby can leave Newborn on kg before they leave it on cm.

Does the NHS tell me to measure before I buy?

The NHS newborn kit page lists how many sleepsuits and vests to have, not how to take a centimetre figure. Measurement for clothes is a retailer-chart job. Measurement for growth is a clinic job. Keep those two uses apart.

In shortLie baby flat, crown to heel, write the centimetres, then open that brand's body-measurement chart. Use the red-book clinic length only as a dated official figure — not as a home centile, and not as the sewn length of a sleepsuit.

How often should I re-measure for clothes?

Before each online order in the first months, and whenever toes hit the end of a footed suit. C&A notes that early growth crosses a 6cm size step in roughly a couple of months. That is a clothes-shopping observation, not a growth-chart rule. If you are worried about length or weight as health, ask the health visitor — do not treat the shopping tape as the answer.