Most dog costumes that get returned were the right costume in the wrong size. Measuring a dog for a Halloween costume takes three numbers, and pet costume sizing isn't standardised the way human clothing is — a "Medium" from one brand can fit like a "Small" from another.
Measuring a Dog for a Halloween Costume: The Three Numbers
- Neck: wrap a soft tape around the base of the neck where a collar normally sits. Leave room for two fingers.
- Chest (girth): measure the widest part of the ribcage, just behind the front legs. This is the measurement that decides whether a vest or harness-style costume closes at all.
- Back length: from the base of the neck (where the collar sits) to the base of the tail. This decides whether a costume rides up or drags.
Write all three down before you look at a size chart. If your dog is between sizes, size up on chest girth first — a costume that's slightly long is fine, one that's tight across the chest is not.
Hats, Headpieces and Wings
Costume accessories like a pumpkin hat or a lion mane only need the neck or head circumference. Measure around the head just in front of the ears, and check the chin strap is elastic — a fixed strap is the most common reason a hat gets pawed off in under a minute.
What the Size Charts Here Actually Cover
Costume listings differ in which measurement they care about, so the three numbers matter in different combinations:
- Vest and harness styles live or die on chest girth. The pumpkin vest harness is sized for small animals, small dogs and cats included, so girth is the number to check first.
- Full garments need all three. The hot dog costume is listed as suiting puppies, adult dogs and cats alike, which only works if you go by measurements rather than by life stage.
- Printed chest-and-back panels, like the spider costume, say outright to check the size chart against your pet's measurements before ordering.
- Head accessories ignore chest and back entirely. A pumpkin hat or a lion mane hat needs head circumference and nothing else.
Measuring a Cat Is a Different Job
Cats carry their width differently and object to the tape more, so take the chest measurement while the cat is standing and settled rather than held. Expect a narrower usable range too: the skull face accessory is built specifically for cats rather than scaled down from a dog pattern, and a cat-shaped chest does not sit comfortably inside a dog vest of nominally the same size.
If your cat will not tolerate the tape at all, a head accessory is the safer purchase, because head circumference is much easier to estimate from an existing collar than chest girth is from a guess.
Quick Fit Check on the Night
- Your dog can sit, lie down and walk normally.
- Nothing covers the eyes, ears or nose.
- You can slide two fingers under every strap.
- No dangling pieces long enough to chew.
Order in Time, or Order for Next Year
Delivery takes three to five weeks. If you are measuring in the second half of October and do not already own a costume, the honest answer is that this year's 31st has gone — measure now and order for next season, or choose something that carries through Thanksgiving and Christmas as well. Shipping is free to the US, UK, Canada, Australia and New Zealand, and returns stay open for 30 days.
How long should a dog wear a costume? Short sessions — a photo, a walk around the block, the first half of a party. Most dogs are done after 30–60 minutes, and taking it off before they're stressed is what makes them tolerate it next year.
Browse the full Pet Halloween & Costumes collection — every listing includes a size chart in the product description.