Thou to Meters (thou to m)

1 thou equals 0.0000254 meters exactly.

1 thou = 0.0000254 meters

How to convert thou to meters

To convert thou to meters, multiply the number of thou by 0.0000254. This factor is exact. To go the other way, multiply meters by 39,370.07874 (rounded).

meters = thou × 0.0000254

Example: 10 thou = 0.000254 meters.

About these units

Thou (thou)

US & ImperialCurrent unit

One thousandth of an inch (0.0254 mm), also called a mil. Used in machining, plastics and the thickness of films and wire.

Machinists say a part is out by a few thou, and the word is a clipping of thousandth, keeping only the first syllable. In North America the same length is often called a mil, which is easy to confuse with a millimetre in international drawings. One thou is a thousandth of an inch, which is exactly 0.0254 mm or 25.4 micrometres, so about 39 of them fit in a millimetre. The word is both singular and plural.

Joseph Whitworth pressed in 1857 for engineers to think in decimal thousandths instead of fractions of an inch, a habit that needed vernier calipers and micrometers to put into practice. Today the unit describes the thickness of paper, foil, wire, plastic sheet and paint films, with a plastic ID card about 30 thou thick. It also appears in older spark-plug gaps, gasket thicknesses and circuit-board geometry. For finer work, a tenth, meaning 0.0001 inch or 2.54 micrometres, is common, and gauge blocks are often given in millionths or in micrometres.

1 thou = 0.0000254 meters (exactly).

Sources: Wikipedia: Thou (unit); Wiktionary: thou

Meter (m)

Metric (SI)Current unit

The SI base unit of length. Since 1983 it is defined as the distance light travels in a vacuum in 1/299,792,458 of a second.

Meter comes from the Greek metron, a measure. In 1791 the French National Assembly defined it as one ten-millionth of the distance from the equator to the North Pole along a great circle through Paris, after rejecting the length of a seconds pendulum because that length changes with local gravity. The surveyors Delambre and Méchain measured the meridian arc, and in 1799 a platinum bar known as the Mètre des Archives became the physical standard. NIST notes that this Earth-based meter turned out to be about 0.2 mm shorter than the true pole-to-equator fraction it was meant to represent.

The 1875 Treaty of the Meter created the CGPM and the BIPM to look after common standards, and in 1889 a platinum-iridium prototype bar took over; the original is still kept at the BIPM. In 1960 the meter was tied to 1,650,763.73 wavelengths of an orange-red krypton-86 line, and in 1983 to the speed of light, which made length a quantity derived from the time standard. The 2018 revision reworded that definition without changing the meter's size. NIST offers a handy yardstick for scale: a pace, meaning two steps, is roughly a meter or a yard.

The meter is the reference unit for length on this site.

Sources: BIPM: history of the metre; NIST: the meter and the SI redefinition; Wikipedia: Metre

Related conversions

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