Getting your system plumbed up, but you don’t know what to order? The outlet, the inlet, the bushing you pulled out of a drawer — what size are they? Guess wrong and you’re waiting even longer for the right part – taking multiple trips to the store or weeks waiting for orders.

Print this one-page PDF at 100% scale and hold your fittings up to the circles. Male threads match the outer circle, female bores match the inner circle. Whatever size they land on is what you order. Covers 1/8″ through 2″ NPT.

The zigzag inside each circle is the thread pitch at 1:1 — lay a fitting’s threads along it to double-check TPI. The squares and ruler on the page (1″ and 1cm) let you confirm the print scaled correctly. Reference the small ruler for gauging fitting lengths.

Do not let your printer “Fit to Page.”

Use “Actual Size” or “100%.”

Dimensions are from ANSI B1.20.1. Accurate enough to ID anything in your fittings drawer. For production-critical work, use a real thread gauge.