Generally, the most accurate way to determine your dog's collar size is by measuring your dog's neck. Measure at the narrowest point of your dog’s neck, just as tight or loose as you would like the new collar to fit.
The collar should be snug, without being so tight that it will cause discomfort or loose enough to slide over your dog’s head.
As a rule of thumb, a well-fitting collar should leave just enough room for you to slide two fingers between the collar and your dog’s neck.
Measuring your current collar
If you are satisfied with the fit of your dog’s current buckle collar, you can measure the collar itself to get a new collar that fits the same.
Measure from the buckle's center bar, where it connects to the collar, to the hole that you are currently using.
The GI Collar is quite possibly the best leather collar for strong and big dogs. Originally, this double-layer leather dog collar was supplied to dog handlers at the former Plattsburgh, NY, Air Force Base, which is how it got its name.
Constructed of two layers of high quality full grain bridle leather with an extended dee ring pattern for additional strength. The layers are stitched together with heavy-duty nylon thread and the edges are beveled and hand finished to assure comfort. Bright nickel-plated welded dee ring and strong roller buckle with a wire tuck loop keeper and smooth capped rivets complete the assembly.
Quality full-grain bridle leathers are some of the most durable leathers available. If wet or soiled, leather should be allowed to air dry. (Never dry your collar or leash in direct heat!) Once dry, gently clean using a damp cloth.
To nourish and help repel dirt and oils, treat the leather with a light coating of a product such Leather BriteTM conditioner or a neutral-colored leather balm. Apply according to the product's instructions.