Difference Between DIN and ISO Bolts
DIN and ISO bolts are made to German and international standards. For most common bolts they are interchangeable in strength and thread, but a few sizes have different spanner (across flats) dimensions.
What DIN and ISO mean
DIN standards were written by the German standards institute and became the reference for metric fasteners worldwide. ISO standards later replaced many of them internationally, and Indian IS standards largely follow ISO.
Where they are the same
For most hex bolts, nuts and allen bolts the thread pitch, strength grades and overall dimensions match, so DIN and ISO parts can be used together.
Where they differ
A few sizes have a different width across flats on the hex head, which means a different spanner size. Some nut heights also differ. If a drawing calls for one standard, mixing the other can affect fit in tight spaces.
Which should you order?
Order the standard named on your drawing or the one your existing parts follow. If unsure, send a sample or photo and we will match it.
