How to Measure Your Son
Boys 4–7 covers numeric sizes 4, 5, 6, and 7, plus the bridging sizes 4/5, 5/6, and 7/8 from some brands. Boys' sizing at this age is typically slimmer through the waist and a touch shorter through the body than girls' sizing at the same numeric size. Take measurements in light clothing with the tape level and snug but not tight.
Height: Have your son stand against a wall, heels flat and barefoot, and measure from the top of the head to the floor. This is the fastest-changing measurement at this age and the best starting point for picking a size.
Weight: Use a home scale. Weight is a useful sanity check for athletic gear and outerwear, where fit needs to accommodate layering or movement.
Chest: Measure around the fullest part of the chest, keeping the tape level under the arms. Used for tops, jackets, and rash guards.
Waist: Find the natural waistline — the narrowest part of the torso, just above the belly button — and measure there. Used for bottoms, shorts, and swim trunks.
Inseam: Have him stand straight and measure from the crotch seam down to the ankle. Especially useful for jeans, pull-on pants, and athletic bottoms.
Pro tip: Athletic brands (Adidas, Nike, Under Armour) are cut slim and may feel snug through the chest and shoulders. If he's on the edge of a size or likes room to move, size up one.
Pro tip: Boys in this range often outgrow length before width. If height puts him in the next size but chest and waist don't, go up for length — cuffing a sleeve is easier than extending one.
Pro tip: Some brands run large (Appaman). Others run true to athletic cut. Check Brand Notes on the product page before sizing.