How to measure for a martingale / half-choke collar:

1. Use a soft measuring tape
You can also use a piece of string and measure it against a ruler.

2. Measure three areas
- Top of the neck (just behind the ears): This is where the collar will sit when it tightens.
- Middle of the neck: The typical resting position for the collar when relaxed.
- Widest part of the head: Around the ears and jaw, to ensure the collar can slide over the head.

3. Choose the correct collar size
Select a size where all three of your measurements fall within the collar’s adjustable range. This ensures the collar fits properly when both relaxed and tightened.

4. Check the fit using the two-finger rule
Once fitted, you should be able to slide two flat fingers (side by side) between the collar and your dog’s neck. This ensures it's snug but not too tight.