Measure the dog's neck circumference, but how?
In the meantime, this topic has become an incomprehensible topic. Some dog collar manufacturers calculate the buckle, others don't and and and... how else is this supposed to be understood?
It's best to delete everything and start again 😊
It's about your dog's neck size and you shouldn't be interested in how dog collar manufacturers calculate it, but rather how you correctly measure the actual neck size.
If you have a tape measure, place it around the dog's neck, about halfway down the neck. Now your index finger and middle finger must fit comfortably between the measuring tape and your neck (fingers next to each other), loosely, not too tight and not too baggy. Hold the measuring tape where it meets, remove and read.
Not everyone has a tape measure at home, no problem either. Take gift ribbon, shoelaces or whatever else “long” you can get your hands on. Now put the string back around the dog's neck with your two fingers (important: the end of the string must be the beginning so that you can calculate it more easily later). Hold the other end of the string with two fingers after measuring. Now you take a ruler or folding ruler and put on the string... and voila, again you have the actual neck circumference of your dog.
Make sure that you always lie roughly in the middle with an adjustable dog collar.
For example, with a neck circumference of 30 cm. Should you choose a collar that can be adjusted by 25-35 cm, so that clothes also fit under it in winter and the dog collar can withstand slight weight fluctuations or coat changes.