How to measure the dog size? Chest: measure the thickest part of the chest, add 2~3CM will be better. (Usually behind the two legs) Length: Make sure your dog stands properly, not sitting or lying. Measure along the dog's backbone from the base of the neck to 5CM front the base of the tail. Neck: the girth of the neck, add 2~3CM will be better.Note:If your dog is a large chest, long hair, or at the high end of the size, you may order the next larger size to ensure a comfortable fit.Size Details: This dog clothes is for small toy dogs or cat under 20 pounds Size S: Neck: 23cm/9.0inch Back: 20cm/8.0inch Chest: 32cm/12.5inch; for weight:3-4 pounds/1.36-1.81 KG Size M: Neck: 26cm/10inch Back: 25cm/9.5inch Chest: 37cm/14.5inch; for weight: 4-5 pounds/1.81-2.27 KG Size L: Neck: 29cm/11.5inch Back: 30cm/11.5inch Chest: 42cm/16.5inch; for weight: 6-10 pounds/2.72-4.54 KG Size XL: Neck: 32cm/12.5inch Back: 35cm/13.5inch Chest: 47cm/18.5inch; for weight: 11-15 pounds/4.99-6.8 KG Size XXL: Neck: 35cm/13.5inch Back: 40cm/15.5inch Chest: 52cm/20.5inch; for weight: 16-20 pounds/7.26-9.07 KGbr>Breed recommed: (for reference only): Size XS: Teacup, Puppies Size S/M: Chihuahua, Toy Poodle Size L: Yorkshire Terrier, Pomeranian, Maltese Size XL/XXL: Pekingese, Jack Russell, Shih TzuThe recommend weight is just for reference, please kindly take a measurement of your dog before buy,thanks.