Convert mils to inches, mm, µm, cm, meters, and feet. Includes thickness reference for PCBs, coatings, foils, and common materials.
A mil — also known as a "thou" — is one thousandth of an inch (0.001 in, or 25.4 µm). It is the standard unit for measuring thin dimensions in American manufacturing: PCB board and copper thicknesses, coating and paint layers, wire diameters, plastic films, and machining tolerances across many production workflows and quality-control checks in industrial settings.
This mil conversion calculator converts between mils and six other length units in one step: inches, millimeters, micrometers (µm), centimeters, meters, and feet. Enter a value in any unit and instantly see all the others. Preset buttons load common industrial values like 62 mil (standard PCB thickness), and a 12-row reference table lists everyday materials and their mil thicknesses.
Whether you are a PCB designer, coating engineer, machinist, or packaging specialist, this tool gives you the precise unit conversions you need — without hunting through separate tables or doing manual 25.4 arithmetic.
US manufacturing specs, PCB design tools, and coating standards all speak in mils, while metric-country suppliers use µm and mm. Converting between them requires dividing or multiplying by 25.4 — easy to miscalculate under pressure. This tool does it instantly for seven units, with a reference table that sanity-checks your result against known material thicknesses.
All conversions route through mils: mil = value × (from-unit factor). Key: 1 mil = 0.001 in = 0.0254 mm = 25.4 µm. 1 in = 1,000 mil; 1 mm ≈ 39.37 mil.
Result: 0.062 in / 1.5748 mm / 1574.8 µm
62 mil is the standard thickness of a 4-layer FR4 PCB. That equals 0.062 inches, 1.575 mm, or 1,574.8 µm.
The mil is deeply embedded in PCB design culture. Trace widths (6, 8, 10 mil), via drill sizes (10–20 mil), pad diameters, and board thickness (62 mil) are all historically specified in mils. Modern design tools like Altium and KiCad support both mil and mm, but many legacy designs and manufacturer capabilities are still quoted in mils.
Industrial paint and powder-coat thickness is measured in mils using dry-film thickness (DFT) gauges. Automotive OEM paint is typically 4.5–5.5 mil total (primer + base + clear). A repainted panel may show 8–12 mil, flagging collision repair. Converting between mil and µm readings is essential when working with European-calibrated gauges.
The word "thou" comes from "thousandth," referring to one thousandth of an inch. US machinists have used this unit since the 19th century. Although SI (metric) is the global standard, mils remain entrenched in US precision manufacturing, especially where legacy tooling and documentation exist.
A mil is one thousandth of an inch (0.001 inch). It is also called a "thou" (from "thousandth"). One mil equals 25.4 micrometers or 0.0254 millimeters.
No. A mil is about 39 times smaller than a millimeter. 1 mm ≈ 39.37 mil, and 1 mil = 0.0254 mm.
A standard 4-layer FR4 PCB is 62 mil (1.57 mm). Thin boards may be 31 mil, and thicker ones 93 or 125 mil.
Mils are the historic US manufacturing standard for thin dimensions. PCB design tools, wire gauges, and coating specs in the US have used mils for decades. International contexts prefer µm or mm.
One millimeter equals approximately 39.37 mils.
Automotive paint: 4–5 mil; powder coat: 2–5 mil; conformal coating: 1–5 mil; anodizing: 0.5–3 mil.