How Is The Size Of A Wrench Determined?
How Is The Size Of A Wrench Determined? Multiply the first number which is the bolt size in inches or millimeters, by 1.5 using a pocket calculator, if necessary. For example, for the numbers in Step 1, 1/2 x 1.5 = . 75 or 3/4, which is the wrench size needed for this standard-sized bolt.