Why a child can fall between sizes
Children do not always match one size neatly. Height, chest, waist and hip measurements can point to different sizes, and two garments in the same labelled size may fit differently. The useful first step is to work out which measurement matters most for the item you are buying, rather than choosing by age alone.
As general sizing advice, age labels are a starting point, not a substitute for measurements. A child who is tall for their age might need more length, while another child of the same age may need more room around the chest or waist. Think, too, about how you want the garment to fit: close-fitting sleepwear and a coat worn over a jumper do not need the same amount of room.
Take measurements before checking the size
Use a flexible tape measure and have your child stand naturally in light clothing. Keep the tape level and comfortably close to the body without pulling it tight.
Measure the parts relevant to the garment. For a top or coat, that will usually include chest and height; for bottoms, waist and hips are useful. If length matters, note the child’s height as well.
Write the numbers down, including the date. Children grow, so an old measurement may not be reliable when you order later.
Compare the measurements with the size information for the item, if it is available. If one measurement points to a larger size than the others, consider whether that part needs extra room for comfort or movement.
Measurements are not always perfectly exact. As a general rule, take each one twice and repeat it if the results differ. Do not add extra centimetres to a body measurement unless the sizing instructions ask you to; the allowance built into a garment is a separate matter.
Think about the fit you need
Consider what your child will wear underneath. A light top needs less room than a jumper under a coat. For sleepwear, think about whether your child prefers a relaxed fit, while making sure you follow any care and safety instructions on the label. For everyday clothes, ask whether the child needs room to bend, sit and move comfortably.
It can also help to check a similar garment your child already owns. Lay it flat and measure the same areas, then compare those figures with the item’s measurements if they are provided. This is only a useful comparison when the existing garment fits well and is a similar style; a roomy coat, for example, is not a good guide to a closer-fitting top.
Allow for the fact that measurements and garment dimensions can vary slightly. For the styles below, the measurement allowance is 2–3cm either way, so avoid treating a small difference as a guarantee of an exact fit.
How the featured kids’ styles size
These four styles all come up small: Kids' Autumn Denim Shirt Two-Piece Set, Boys' Mid-Length Spring Trench Coat – Kids' Overcoat, Kids' Gingham Pyjama Romper and Older Kids' Long Velvet-Lined Coat.
For a two-piece outfit or a coat, pay particular attention to the measurements that affect movement and layering. With a romper, consider both the child’s height and how the fit will feel when they sit or stretch. These are general ways to think through fit; the sizing advice above applies to each of the linked styles.
Before you place the order
Check that you have measured the child recently, used the measurements that matter for the garment and allowed for what they will wear with it. If the item has a size guide, use its measurements rather than assuming that a familiar label will fit exactly the same as another brand. Keep the measurement notes handy when comparing options, and follow the care and safety instructions on the label once the garment arrives.
Our recommendation: For any of these four styles, choose the larger size when your child is between sizes; the styles come up small, so sizing up gives you a better chance of avoiding a too-snug fit.