Points of the compass

The points of the compass are the vectors by which planet-based directions are conventionally defined. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each separated by 90 degrees, and secondarily divided by four ordinal directions—northeast, southeast, southwest, and northwest—each located halfway between two cardinal directions. Some disciplines such as meteorology and navigation further divide the compass with additional vectors. Within European tradition, a fully defined compass has 32 'points'.
Compass points are valuable in that they allow a user to refer to a specific azimuth in a colloquial fashion, without having to compute or remember degrees.

Compass points

The names of the compass point directions follow these rules:

8-wind compass rose

32-wind compass rose

In summary, the 32-wind compass rose is yielded from the eight principal winds, eight half-winds and sixteen quarter-winds combined together, with each compass direction point at an ° angle from the next.
In the mariner's exercise of boxing the compass, all thirty-two points of the compass are named in clockwise order.

Traditional names

The traditional compass rose of eight winds was invented by seafarers in the Mediterranean Sea during the Middle Ages. The traditional mariner's wind names were expressed in Italian, or more precisely, the Italianate Mediterranean lingua franca common among sailors in the 13th and 14th centuries, which was principally composed of Genoese, mixed with Venetian, Sicilian, Provençal, Catalan, Greek and Arabic terms from around the Mediterranean basin.
This Italianate patois was used to designate the names of the principal winds on the compass rose found in mariners' compasses and portolan charts of the 14th and 15th centuries. The "traditional" names of the eight principal winds are:
Local spelling variations are far more numerous than listed, e.g. Tramutana, Gregale, Grecho, Sirocco, Xaloc, Lebeg, Libezo, Leveche, Mezzodi, Migjorn, Magistro, Mestre, etc. Traditional compass roses will typically have the initials T, G, L, S, O, L, P, and M on the main points. Portolan charts also colour-coded the compass winds: black for the eight principal winds, green for the eight half-winds, and red for the sixteen quarter-winds.
Each half-wind name is simply a combination of the two principal winds that it bisects, with the shortest name usually placed first, for example: NNE is "Greco-Tramontana"; ENE is "Greco-Levante"; SSE is "Ostro-Scirocco", etc. The quarter winds are expressed with an Italian phrase, "Quarto di X verso Y", or "X al Y" or "X per Y". There are no irregularities to trip over; the closest principal wind always comes first, the more distant one second, for example: north-by-east is "Quarto di Tramontana verso Greco"; and northeast-by-north is "Quarto di Greco verso Tramontana".

32 compass points

The table below shows how the 32 compass points are named.
Each point has an angular range of 11.250 degrees where: middle azimuth is the horizontal angular direction of the given compass bearing; minimum is the lower angular limit of the compass point; and maximum is the upper angular limit of the compass point.
No.Compass pointAbbreviationTraditional wind pointMinimumMiddle azimuthMaximum
1North by eastNbEQuarto di Tramontana verso Greco5.625°11.250°16.875°
3Northeast by northNEbNQuarto di Greco verso Tramontana28.125°33.750°39.375°
5Northeast by eastNEbEQuarto di Greco verso Levante50.625°56.250°61.875°
7East by northEbNQuarto di Levante verso Greco73.125°78.750°84.375°
9East by southEbSQuarto di Levante verso Scirocco95.625°101.250°106.875°
11Southeast by eastSEbEQuarto di Scirocco verso Levante118.125°123.750°129.375°
13Southeast by southSEbSQuarto di Scirocco verso Ostro140.625°146.250°151.875°
15South by eastSbEQuarto di Ostro verso Scirocco163.125°168.750°174.375°
17South by westSbWQuarto di Ostro verso Libeccio185.625°191.250°196.875°
19Southwest by southSWbSQuarto di Libeccio verso Ostro208.125°213.750°219.375°
21Southwest by westSWbWQuarto di Libeccio verso Ponente230.625°236.250°241.875°
23West by southWbSQuarto di Ponente verso Libeccio253.125°258.750°264.375°
25West by northWbNQuarto di Ponente verso Maestro275.625°281.250°286.875°
27Northwest by westNWbWQuarto di Maestro verso Ponente298.125°303.750°309.375°
29Northwest by northNWbNQuarto di Maestro verso Tramontana320.625°326.250°331.875°
31North by westNbWQuarto di Tramontana verso Maestro343.125°348.750°354.375°

Half- and quarter-points

By the middle of the 18th century, the 32-point system had been further extended by using half- and quarter-points to give a total of 128 directions.
These fractional points are named by appending, for example east, east, or east to the name of one of the 32 points. Each of the 96 fractional points can be named in two ways, depending on which of the two adjoining whole points is used, for example, NE is equivalent to NbEN. Either form is easily understood, but alternative conventions as to correct usage developed in different countries and organisations. "It is the custom in the United States Navy to box from north and south toward east and west, with the exception that divisions adjacent to a cardinal or inter-cardinal point are always referred to that point." The Royal Navy used the additional "rule that quarter points were never read from a point beginning and ending with the same letter."
Compass roses very rarely named the fractional points and only showed small, unlabelled markers as a guide for helmsmen.

128 compass directions

The table below shows how each of the 128 directions are named. The first two columns give the number of points and degrees clockwise from north. The third gives the equivalent bearing to the nearest degree from north or south towards east or west. The "CW" column gives the fractional-point bearings increasing in the clockwise direction and "CCW" counterclockwise. The final three columns show three common naming conventions: No "by" avoids the use of "by" with fractional points; "USN" is the system used by the US Navy; and "RN" is the Royal Navy system. Colour coding shows whether each of the three naming systems matches the "CW" or "CCW" column.

Chinese compass points

Navigation texts dating from the Yuan, Ming, and Qing dynasties in China use a 24-pointed compass with named directions. These are based on the twelve Earthly Branches, which also form the basis of the Chinese zodiac. When a single direction is specified, it may be prefaced by the character 單 or 丹.
Headings in-between the 24 compass points could be described by combining point names. For instance, 癸子 refers to the direction halfway between point 子 and point 癸, or 7.5°. This technique is referred to as a double-needle compass.
PointOrdinal NameAngle
子 zǐnorth
癸 guǐ15°
丑 chǒu30°
艮 gěnnortheast45°
寅 yín60°
甲 jiǎ75°
卯 mǎoeast90°
乙 yǐ105°
辰 chén120°
巽 xùnsoutheast135°
巳 sì150°
丙 bǐng165°
午 wǔsouth180°
丁 dīng195°
未 wèi210°
坤 kūnsouthwest225°
申 shēn240°
庚 gēng255°
酉 yǒuwest270°
辛 xīn285°
戌 xū300°
乾 gānnorthwest315°
亥 hài330°
壬 rén345°