Inches Per Second to Knots (in/s to kn)

1 inch per second equals 0.04937365011 knots (rounded).

1 inch per second = 0.04937365011 knots

How to convert inches per second to knots

To convert inches per second to knots, multiply the number of inches per second by 0.04937365011. The factor is rounded to 10 significant digits. To go the other way, multiply knots by 20.25371829 (rounded).

knots = inches per second × 0.04937365011

Example: 10 inches per second = 0.4937365011 knots.

About these units

Inch Per Second (in/s)

US & ImperialCurrent unit

Exactly 0.0254 m/s. Used for tape speeds.

Tape recording standardized on inch per second, often written ips. The Compact Cassette, introduced by Philips in August 1963, runs at 1 7/8 ips, which is 4.7625 cm/s, since 1.875 times 2.54 gives that figure. Open-reel machines used a ladder of speeds, each double the one below: 3 3/4 ips (9.525 cm/s), 7 1/2 ips (19.05 cm/s), 15 ips (38.1 cm/s) and 30 ips (76.2 cm/s).

Some dictation machines ran at half the cassette speed, 15/16 ips, or about 2.38 cm/s. The unit rests on the international inch of exactly 25.4 mm, so one inch per second is exactly 0.0254 m/s, and NIST lists the conversion as exact. A cassette moves at about 0.0476 m/s, which is 0.171 km/h.

1 inch per second = 0.0254 meters per second (exactly).

Sources: Wikipedia: Compact Cassette; NIST SP 811 Appendix B.8: conversion factors; Wikipedia: Orders of magnitude (speed)

Knot (kn)

NauticalCurrent unit

One nautical mile per hour, exactly 1.852 km/h. The unit of speed for ships, aircraft and wind.

Knots in a rope really were counted. Before the mid-nineteenth century, sailors threw a weighted wooden board, the chip, off the stern on a line called the log-line. The line carried knots at regular intervals, and a sailor counted how many passed through his fingers while another timed the run with a sandglass. William Bourne's A Regiment for the Sea, printed in 1574, is the first known description, and many ships spaced knots 8 fathoms, about 14.6 meters, apart with a glass of roughly half a minute.

Today a knot is one nautical mile per hour, exactly 1,852 meters per hour, about 1.151 mph or 0.514 m/s. A ship making 1 knot along a meridian covers about one minute of latitude per hour, which is why charts and the unit fit together. It is not an SI unit, and the symbol is kn, though kt is common in aviation. Saying knots per hour is wrong, since that would describe acceleration. The US moved civil aircraft standards to nautical miles and knots in 1969, and winds and currents are also quoted in them.

1 knot = 0.5144444444 meters per second (approximately).

Sources: Wikipedia: Knot (unit); Wikipedia: Chip log; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

See all speed units.