Make sure your dog is standing upright and you have your tape measure handy.
The chest (1) measurement should be taken from just behind your dog's front legs. Wrap the tape measure all the way around your dog's chest. We recommend adding a few fingers for comfort.
Between sizes? Try measuring the chest for a fairly snug fit without room for your fingers. Then try measuring again with a few fingers in the tape measure. If your first 'close fit' measurement was already borderline and your 'fingers' measurement pushes the reading into the next size, we suggest going for the next size. If however both measurements fall within the smaller size, opt for the smaller size.
Unless you have wide necked breed such as a Pug or a Bulldog, you almost certainly don't need to measure the neck line.