I had to order 3 and return 2 to get the right size.  I have 2 older Carhartt Men's Journeyman Belts  that are a 50 size  [black and brown]
I had to return earlier ones of those as 'my size' was way too big,  as it is,  i've drilled at least 6 to 8 holes to make those fit.
i have lost some weight  [yeah]  and while i did wear pants at a 54 back then.....
My actual size now, using a cloth tape is about 51,  but i do have some pants that are a 50

below is the Carhartt 'size'  how long the leather actually is,  and hole to buckle is longest farthest hole to end of leather belt
New Carhartt belts.  May 2018
Size.  Leather measure.  Hole to buckle
50  54  51
48  53  49  1/2
46  51  48

i kept the 46  !!!!!! which actually fit,  but i wish i was really down that far!!

some reviews have said that a 48 was too small  [short]  what universe are they in??!?

Other than measurements,  these are great quality  [as most carhartt stuff is]
These are made of good leather and metal,  and have lasted 8 years and while are worn,  still are OK
So,  not cheap,  but end up being OK per year  LOL