TL;DR
Build each age band from its own measurements, leave growth room at the seat and sleeve, confirm the safety route for the destination market, then approve one sample per band rather than per size.
Age bands are not measurements
A size labelled for twelve months describes a market convention rather than a body. Newborn Halloween costumes and infant Halloween costumes are bought by parents who read height and weight, so publish both next to the size label and note the weight range as well, since two children of the same height can differ by several kilograms. Keep the same measurement points across the run.
Toddler costumes add a second variable: movement. A toddler walks, climbs and sits on the floor, so the seat seam, knee allowance and sleeve opening all need more room than the equivalent chest measurement suggests.
What changes from newborn to toddler
Newborn and infant styles are mostly worn once, for a photograph or a short event, so closures and comfort matter more than durability. Snap plackets, soft hoods and covered seams do more for a baby pumpkin costume than a heavier fabric would.
Toddler styles are worn repeatedly. A toddler witch costume, a toddler skeleton costume or a toddler spiderman costume has to survive a party, a school day and a second outing, which moves the emphasis to seam strength, stretch recovery and print durability. A garment that photographs well on a folded blanket can still be unwearable once a baby is lifted and held, so check the neck opening and the leg length on a moving child rather than on a table.
Safety paperwork belongs to the band
Childrens products carry their own compliance route. In the United States the Childrens Product Certificate process sets out the testing and documentation for childrens items, and the CPSC clothing guidance covers apparel questions including flammability. Ask for the test summary that matches the age band you are buying, because a report written for a three year old style does not cover a newborn design.
Confirm the destination market before sampling, not after. Small parts such as eyes, pom poms and zip pulls, cord lengths around the neck and the way a cape fastens are all decisions that are cheap at pattern stage and expensive at inspection, which is why supplier checks belong in the first meeting.
Pack ratios for multi-size programmes
A multi-size programme needs a ratio per carton, not a flat quantity per size, the same logic that drives the buying windows in our costume range planning guide. Retail buyers usually want the middle sizes to dominate, with newborn and the largest toddler size as the smallest share, and the ratio should be stated in the purchase order.
Ratios also drive the pattern work. When the smallest band and the largest band are cut from the same block with different grading, check that the smallest size still closes cleanly and the largest still holds its shape on a filled sample. State the ratio in the purchase order and repeat it on the carton label so the warehouse does not re-sort.
Approve samples across the band
Approve one sample per age band rather than one per size, and keep the measured sheet with it. A toddler ghost costume that fits at the smallest size tells you very little about the largest size unless the grading was checked separately.
Shanghai Haitailu Clothing Co., Ltd builds production to the buyer measurement sheet and can review a child size run against its catalogue at www.festivocostumes.com. Care labels, fibre content and packaging are confirmed with the same approved sample so the record stays in one place.