Convert yards to millimeters

A millimeter is one thousandth of a meter. The meter is the SI base unit of length and takes its value from the speed of light in vacuum[1]. The milli prefix divides the meter into a thousand equal parts, and the millimeter is the graduation you can see on a ruler and on a tape measure.

The yard comes from a different system of measures and takes its present length from the meter. The international agreement of 1959 set the yard at exactly 0.9144 meter, and the value has applied since July 1 of that year[2]. In millimeters that gives exactly 914.4, and this is the only number you need to remember.

A yard holds three feet, and each foot holds twelve inches, so the whole yard holds 36 inches. That division is handled by the yards to feet converter. An inch measures exactly 25.4 millimeters[2], so both multipliers on this page are exact values. That ratio on its own is handled by the inches to millimeters converter.

One yard is exactly 914.4 millimeters. To turn yards into millimeters you multiply the value by 914.4. The multiplier follows straight from the definition of the yard, so the result keeps its full accuracy.

Three values come out of that calculation and return in the tables below. Half a yard is 457.2 millimeters. Two yards give 1,828.8 millimeters. Ten yards come to 9,144 millimeters, which is 9.144 meters.

The same multiplier works for fractional values: one hundredth of a yard is 9.144 millimeters and one thousandth is 0.9144 millimeter.

You can write the remainder of a yard in inches, because a yard holds 36 of them. The input field takes that notation directly: 2 yd 18 in gives 2,286 millimeters, and so does 2.5 yd.

Fractions of a yard use the same multiplier. A quarter of a yard is 228.6 millimeters, and one eighth gives 114.3 millimeters. Every eighth of a yard ends one place after the decimal point, because the multiplier carries a single decimal.

The calculation takes one step: you multiply the number of yards by 914.4. The multiplier is an exact value, so the number of digits in the result depends on the value you enter.

Take 54 yards as the example. Fifty-four times 914.4 gives 49,377.6 millimeters. The same length measures 49.3776 meters.

The same conversion can be written out as a chain, where each step turns one unit into the next. This is the form known as dimensional analysis. You multiply fifty-four yards by three, because a yard holds three feet, and you get 162 feet. You multiply that by twelve, because a foot holds twelve inches, and you have 1,944 inches. Finally you multiply by 25.4, because an inch measures that many millimeters[2], and you arrive at 49,377.6 millimeters.

Both routes end on the same number, because the product 3 × 12 × 25.4 is exactly 914.4. The chain helps when the calculation has to be shown step by step, and the single multiplier helps when only the result matters.

The conversion in the other direction is a division by 914.4 and it is handled by the millimeters to yards converter. For longer distances the yards to meters converter reads more easily, and for fabric there is the yards to centimeters converter.

For a single value the field above is quicker. For a whole column of lengths it pays to write the formula once and drag it down.

In Excel the formula takes the form CONVERT(number, from_unit, to_unit). The yard carries the code "yd", so for a value in cell A1 you type =CONVERT(A1,"yd","mm")[5].

Excel builds the code "mm" from two parts: the first m is the milli prefix and the second m is the meter[5]. The unit list in the documentation therefore carries the meter alone, and you add the prefix from a separate table. The codes "cm" and "km" are formed the same way.

Without the function a plain multiplication does the job: the formula =A1*914.4 gives the same result and works in Google Sheets and LibreOffice Calc as well. Before you drag the formula down the column, put the value 1 in cell A1 and check that the result reads 914.4.