# Nautical miles versus statute miles. What's the difference? **URL:** \ **Category:** Factual Questions\ **Created:** [September 12, 2012, 6:04am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474 "2012-09-12T06:04:24Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![duffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duffer/32/1026_2.png) [@duffer](https://boards.straightdope.com/u/duffer)\ **Post date:** [September 12, 2012, 6:04am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/1 "2012-09-12T06:04:24Z")
That pretty much covers it. Wouldn’t 500 miles on land be the same as on sea when measuring any travel across the globe? If you want to explain knots versus mph as well I’m willing to learn. ---
**Author:** ![W0X0F](https://avatars.discourse-cdn.com/v4/letter/w/b77776/32.png) [@W0X0F](https://boards.straightdope.com/u/W0X0F)\ **Post date:** [September 12, 2012, 6:33am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/2 "2012-09-12T06:33:18Z")
A nautical mile more or less started out as being equal to a minute of latitude. That makes it equal to about 6080 feet, or a little more than 10% larger than a regular (statute) mile. The reason was that it was easier to keep track of on a map where the linear scale wasn’t constant, like a Mercator nautical chart. No matter where you were on the map, one degree of latitude was always 60 nautical miles. So it was commonly used in shipping and later in aviation. It’s still being used to this day. The military aviation weather office I used to work in still measured official wind speeds in knots. Correspondingly, a knot - or nautical mile per hour - is a little more than 10% larger than a regular mile per hour. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [September 12, 2012, 6:36am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/3 "2012-09-12T06:36:36Z")
Nautical miles are longer, for whatever historical reason, that’s all. There’s no reason why we couldn’t measure sea trips in statute miles but it wasn’t and isn’t done that way. A “knot” is just a _nautical_ mile per hour, and your speed in knots used to be measured with a log line. That was a rope with knots every however-many yards - you threw one end of it with a draggy hunk of wood attached over the side while your colleague started a small sand-glass and counted how many knots were pulled through your fingers until he said “Stop”. By a simple piece of arithmetic over the spacing of the knots and the duration of the sand glass, your speed in knots was the number of knots that had run through your fingers. ---
**Author:** ![Floater](https://avatars.discourse-cdn.com/v4/letter/f/dc4da7/32.png) [@Floater](https://boards.straightdope.com/u/Floater)\ **Post date:** [September 12, 2012, 9:01am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/4 "2012-09-12T09:01:06Z")
I once leafed through a 17th century encyclopedia and most every European country had its own basic measurement called mile, at least the terms were translated as mile in English. FWIW, In Norway and Sweden a mile means ten kilometers. ---
**Author:** ![duffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duffer/32/1026_2.png) [@duffer](https://boards.straightdope.com/u/duffer)\ **Post date:** [September 12, 2012, 11:00am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/5 "2012-09-12T11:00:50Z")
Wacky Scandinavians. Thanks for the info everyone! ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [September 12, 2012, 12:24pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/6 "2012-09-12T12:24:19Z")
> [@W0X0F](#): > > Correspondingly, a knot - or nautical mile per hour - is a little more than 10% larger than a regular mile per hour. The difference is actually 15%. To be precise, 1 nautical mile = 1.15078 statute miles. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [September 12, 2012, 12:33pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/7 "2012-09-12T12:33:00Z")
> [@Malacandra](#): > > That was a rope with knots every however-many yards - you threw one end of it with a draggy hunk of wood attached over the side while your colleague started a small sand-glass and counted how many knots were pulled through your fingers until he said “Stop”. According to [Wiki](http://en.wikipedia.org/wiki/Chip_log), the glass had a duration of 28 seconds and the knots were spaced 47 ft 3 in apart. As that article shows, the piece of wood at the end of the line had a rather sophisticated shape. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [September 12, 2012, 12:35pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/8 "2012-09-12T12:35:29Z")
> [@Floater](#): > > I once leafed through a 17th century encyclopedia and most every European country had its own basic measurement called mile, at least the terms were translated as mile in English. > > FWIW, In Norway and Sweden a mile means ten kilometers. cool! didn’t know that. 🙂 ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [September 12, 2012, 12:53pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/9 "2012-09-12T12:53:12Z")
> [@Floater](#): > > I once leafed through a 17th century encyclopedia and most every European country had its own basic measurement called mile, at least the terms were translated as mile in English. > > FWIW, In Norway and Sweden a mile means ten kilometers. To be precise, “mil” is a metric unit in common but not official use, of 10 kilometers, based on the old Swedish and Norwegian landmil (land mile) units that were close to that (but different). nautisk mil (nautical mile) is a unit of 1852 m sjømil (sea mile) is sometimes used for nautical mile, but this is considered erroneous by the pedantic, since the last official definition of sjømil was 7408 m or four nautical miles, which is why nautical miles were called kvartmil (quarter miles). ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [September 12, 2012, 2:12pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/10 "2012-09-12T14:12:17Z")
To quote the great Jack Aubrey - “A nautical mile is somewhat longer, and very much wetter! Ha ha ha ha!” ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [September 12, 2012, 2:35pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/11 "2012-09-12T14:35:33Z")
> [@W0X0F](#): > > A nautical mile more or less started out as being equal to a minute of latitude. That makes it equal to about 6080 feet, or a little more than 10% larger than a regular (statute) mile. The reason was that it was easier to keep track of on a map where the linear scale wasn’t constant, like a Mercator nautical chart. No matter where you were on the map, one degree of latitude was always 60 nautical miles. So it was commonly used in shipping and later in aviation. It’s still being used to this day. The military aviation weather office I used to work in still measured official wind speeds in knots. > > Correspondingly, a knot - or nautical mile per hour - is a little more than 10% larger than a regular mile per hour. If you look at charts used by boaters they commonly do not have a specific scale on them like maps for land based uses. The user of the boating maps know to pick up the scale from the longitude markings. I always thought it sort of a shame that kilometers and nautical miles couldn’t have an easier conversion constant. The both started out as a subdivision of the circumference of the earth. But I guess the metric guys wanted to get away from all that old school 60 and 360 nonsense. ---
**Author:** ![Billdo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/billdo/32/315_2.png) [@Billdo](https://boards.straightdope.com/u/Billdo)\ **Post date:** [September 12, 2012, 7:20pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/12 "2012-09-12T19:20:54Z")
> [@gazpacho](#): > > If you look at charts used by boaters they commonly do not have a specific scale on them like maps for land based uses. The user of the boating maps know to pick up the scale from the longitude markings. One reason for this is that on Mercator projection charts, the length of a mile on the chart varies depending on where (specifically at what latitude) on the chart you are looking. It’s not much of an issue for large scale charts covering local areas, and those will commonly have a scale on them. However, for small scale charts covering large sections of ocean, the length of a mile can vary considerably, and you have to pick it off from the latitude scale. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 12, 2012, 9:08pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/13 "2012-09-12T21:08:43Z")
> [@muldoonthief](#): > > To quote the great Jack Aubrey - “A nautical mile is somewhat longer, and very much wetter! Ha ha ha ha!” And the dog watch is cur-tailed. 🙂 ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [September 12, 2012, 10:36pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/14 "2012-09-12T22:36:49Z")
> [@carnivorousplant](#): > > the dog watch is cur-tailed. 🙂 That actually belongs to Stephen Maturin - though JA was indeed fond of repeating it. ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [September 12, 2012, 10:40pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/15 "2012-09-12T22:40:50Z")
> [@Xema](#): > > The difference is actually 15%. To be precise, 1 nautical mile = 1.15078 statute miles. According to > **[Nautical mile](https://en.wikipedia.org/wiki/Nautical_mile)** > > A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute (.mw-parser-output .sfrac{white-space:nowrap}.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tion{display:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center}.mw-parser-output .sfrac .num{display:block;line-height:1em;margin:0.0em 0.1em;border-bottom:1px solid There is... It is 57,875/50,292 or ~1.1507794480235425117314881094409 > **[57,875/50,292 - Wolfram|Alpha](https://www.wolframalpha.com/input/?i=57%2C875%2F50%2C292)** > > Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels. Brian ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [September 12, 2012, 11:15pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/16 "2012-09-12T23:15:14Z")
I don’t think that’s carried to sufficient decimal places to convey just how much it is not 1.15078. :dubious: ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [September 13, 2012, 6:10am UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/17 "2012-09-13T06:10:28Z")
> [@N9IWP](#): > > According to > [Nautical mile - Wikipedia](http://en.wikipedia.org/wiki/Nautical_mile) > > It is 57,875/50,292 or ~1.1507794480235425117314881094409 > > [57,875/50,292 - Wolfram|Alpha](http://www.wolframalpha.com/input/?i=57%2C875%2F50%2C292) > > Brian So that’s “approximately” as in “to a far higher degree of accuracy than a thousandth of an inch per light-year”, then. ---
**Author:** ![SGT42](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@SGT42](https://boards.straightdope.com/u/SGT42)\ **Post date:** [September 13, 2012, 7:34pm UTC](https://boards.straightdope.com/t/nautical-miles-versus-statute-miles-whats-the-difference/634474/18 "2012-09-13T19:34:56Z")
The statute mile comes from the Roman ‘millia passum’ = 1 thousand steps. It was the measure of 1000 double steps (counted each time the left foot touches the ground) of a Roman legionaire.