Measure your dog’s neck at the base where the harness will sit
Measure your dog’s chest girth around the widest part of the ribcage, just behind the front legs
Measure your dog’s body length if the harness style requires it
Use a soft measuring tape for accuracy
Keep the tape snug but not tight
Check the harness brand’s size chart before buying
Choose the size based on the chest girth first if sizes fall between ranges
Make sure you can fit two fingers under the harness straps
Confirm the harness does not rub under the armpits
Adjust all straps evenly after putting the harness on
Recheck the fit after your dog walks and moves
Measure again if your dog is still growing or has changed weight