The Stubs Iron Wire Gauge system (also known as the Birmingham Wire Gauge) is used in medicine to measure the diameter of hypodermic needles, catheters, and suture wires. It was originally developed in early 19th-century England for use in wire manufacture, and it began appearing in a medical setting in the early 20th century.

The Stubs system was the first wire gauge recognized as a standard by any country when Great Britain adopted it in 1884. Each gauge increment roughly correlates to multiples of .01 inches, but the system is not truly linear, as can be seen in the Needle gauge comparison chart. Also, the needle gauge is inversely proportional to its diameter, so the larger the gauge number, the narrower the diameter.

Another common gauge system is the French catheter scale.

Common needles in medical use use a system of 1/gauge in inches as the sizing.

Needle wire gauge was derived from the Stubs Iron Wire Gauge.