Convert inches to meters

The inch is a length unit of the imperial and US customary systems, written with a double prime, as in 65″. Since 1 July 1959 an inch has measured exactly 25.4 millimeters, which is 0.0254 meters[1]. The value was taken from the meter, so every conversion on this page comes out without rounding.

The inch is divided by halving. The next marks down are a half, a quarter, an eighth and a sixteenth, and that is exactly how the graduations on a US tape measure are laid out. It is where a reading such as 5 3/8 in comes from, and that reading answers to 136.53 millimeters. Twelve inches make a foot and thirty-six make a yard.

The meter is the SI base unit and it is what sets the value of the inch. Since 1983 a meter has been the distance light travels in vacuum in 1/299 792 458 of a second, and the 2019 revision of the SI restated that wording[2]. In the United States both units are in daily use, with inches on lumber, pipe threads, screen diagonals and body height, and meters in science, medicine and athletics[3]. In the European Union an inch figure may stand beside the metric one as a supplementary indication, and Directive 2009/3/EC removed the deadline that once limited this[4].

Pipe sizes carry the word inch in a different sense. A G 1 thread measures 33.249 millimeters across, and G 1/2 measures 20.955 millimeters. The number goes back to the bore of the older steel pipe the thread was made for, and walls have grown thinner since[5]. The inch figure is a trade name there, and the real dimension comes from a thread table.

An inch is 0.0254 meters, or 2.54 centimeters. It takes 39.37 inches to make a full meter.

A single inch turns into such a small number of meters that the conversion earns its keep from a few dozen inches upwards. Twelve inches, a foot, come to 0.3048 meters. Thirty-six inches, a yard, come to 0.9144 meters. Sixty inches, five feet, come to 1.524 meters.

The range from sixty to seventy-five inches covers adult height, because that is how height is written in the United States. A height of 68 inches is 1.7272 meters. A height of 72 inches is exactly six feet, which is 1.8288 meters.

Screen diagonals form the second busy range. A set described as 55-inch measures 1.397 meters across the diagonal, and at a 16:9 ratio its picture is 1.22 meters wide.

The formula has one step: multiply the number of inches by 0.0254.

The multiplier is an exact value, because that is what an inch measures by definition. Dividing by 39.3700787 gives the same answer, except that this number is already rounded and drifts in the later decimal places at large values.

Here is one worked example. Take 65 inches, the diagonal a television carries in its model name. Multiply 65 by 0.0254 and you get 1.651. The screen therefore measures 1.65 meters across.

A dimension written in feet and inches becomes plain inches in one step before it goes into the field above. Multiply the feet by twelve and add the inches. So 5 ft 9 in gives 60 plus 9, which is 69 inches. That works out at 1.7526 meters.

The meters to inches converter works the other way. For smaller dimensions reach for inches to centimeters or inches to millimeters, and for feet on their own take feet to meters.