Only just fit but should have had room to grow

I messured my dog with some waist messuring tape to get an accurate size of the max girth of my dog around his chest ro the area the vest straps on from there photots on amazon.  And choose to buy the vest 25 inch to 30 inchs.  My dog girth was 26 inchs but I had to streatch the vest to the max size and it just fit.  and only just there no room for growth. not sure how this is 30 inchs.  However for the moment it will work but I am not really that pleased