Length Converter

Value_target = Value_source × (Factor_source / Factor_target),  where each Factor is that unit expressed in metres

• 1 in0.0254 m exactly, so 25.4 mm
• 1 ft0.3048 m exactly (12 in)
• 1 yd0.9144 m exactly (3 ft)
• 1 mi1,609.344 m exactly (5,280 ft)
• 1 nautical mile1,852 m exactly by international agreement, and not any whole multiple of the statute mile

• The US survey foot is a separate unit: 1200/3937 metres, about 0.3048006 m. It is 2 parts per million longer than the international foot, which is invisible across a room and 20 cm across 100 km. It was retired for new work at the end of 2022, but decades of state plane coordinates, land parcel descriptions and benchmark elevations are recorded in it, and mixing the two silently shifts survey positions.
• Convert once, from the original reading. Stepping inches to centimetres to metres to feet accumulates rounding at every hop; multiply by a single combined factor instead and round only for display.
• Significant figures do not improve on the way through. A wall measured to the nearest inch is not suddenly known to a hundredth of a centimetre because 25.4 happens to have three digits, so the 175.26 cm above claims precision the tape never had. Round the output back to the precision of the input.