Tool · measurement in, standard out

Pipe size lookup: measure the outside, get the standards

Outer diameter is the number a caliper gives you and the number a fitting is built around. Give it here and see every published standard that matches — then see what else you have to measure to separate them.

Every published outer diameter

20 distinct OD values; 17 of them are shared by more than one material family — for those, the caliper alone cannot name the pipe.

How close is close enough

Published ODs are exact definitions, but a measurement is not: a micrometer on a clean pipe is good to a few hundredths of a millimetre, a tape around a pipe is not a diameter at all. The tolerance says how much disagreement to allow before a standard stops being a candidate — tight for micrometre readings, normal for calipers, loose when you only have a rough idea.

If nothing matches, either the measurement is off or the pipe is outside the standards published here: copper tube (ASTM B88), CPVC and metric tubing are not in the published set yet — what is covered and what is not.