Latitude vs Longitude — Which Is Which (and the Memory Trick That Sticks)

I forget which one runs sideways at least once a year, and I write about coordinates for a living. The trick that finally stuck for me is the ladder: latitude is the rungs of a ladder, running across; longitude is the long vertical poles. If you can hold onto that one image, the rest of the system — signs, ranges, formats, edge cases — falls out naturally.

The mental model in one image

• Latitude = the horizontal rungs of a ladder around the globe. Tells you how far north or south you are.
• Longitude = the vertical orange-slice lines from pole to pole. Tells you how far east or west you are.

A latitude–longitude pair is a single unique point. Every spot on Earth has exactly one.

Latitude: north and south, easy half

Latitude is measured from the equator, the horizontal line halfway between the poles. The equator is 0°. From there:

• North pole: +90° (or 90°N)
• Equator: 0°
• South pole: −90° (or 90°S)

A few landmarks worth memorising:

• London: 51.5°N
• New York: 40.7°N
• Karachi: 24.9°N
• Sydney: 33.9°S (or −33.9°)

Useful intuition: 1° of latitude is about 111 km everywhere on Earth. A latitude change of 0.01° is roughly 1.1 km on the ground. Latitude was the easy half because a sextant reading off the noon sun gives it directly — any decent ship’s captain in 1750 could read latitude from a moving deck.

Longitude: east and west, the hard half

Longitude is measured from the prime meridian, a vertical line that — by an 1884 international vote — runs through the Royal Observatory in Greenwich. Why Greenwich specifically? Mostly because the British already had the most widely used maritime charts and re-printing every chart in the world was unappealing. The story is the history of latitude and longitude post if you want the full version.

• Prime meridian (Greenwich): 0°
• Antimeridian (international date line, roughly): ±180°

• London: 0° (right on the line)
• New York: −74.0° (or 74°W)
• Karachi: 67.0°E
• Tokyo: 139.7°E

Unlike latitude, the real-world distance covered by 1° of longitude depends on where you are. At the equator, 1° of longitude is about 111 km. At the poles, it shrinks to zero (all meridians converge). Around the latitude of Karachi or New York, 1° of longitude works out to roughly 90–95 km.

Which comes first, latitude or longitude?

Almost every human-readable format puts latitude first. When you see 48.858420, 2.294500, the first number is latitude (48.858420°N) and the second is longitude (2.294500°E). This is the order used by Google Maps, Apple Maps, every smartphone, and almost every navigation app you’ll ever paste a coordinate into.

The one big exception: GeoJSON, PostGIS, and many programming geometry libraries put longitude first— [2.294500, 48.858420]. Mathematicians prefer (x, y) order, longitude maps to x, and the geospatial standards bodies followed the math. Loading a GeoJSON file directly into a (lat, lon)-assuming app reflects every point horizontally. I’ve hit this bug more than once.

Quick rule for unfamiliar coordinates: if either number has an absolute value greater than 90, that one is definitely longitude (|lat| can only go up to 90; |lon| can go up to 180). If both numbers are under 90 in absolute value, assume latitude first unless the source explicitly uses GeoJSON convention.

The three formats you’ll see

All three encode the same point in different notations. Need to convert between them? Our free coordinates converter translates DD ↔ DMS ↔ DDM ↔ UTM with one click.

1. Decimal degrees (DD): 40.712776, -74.005974Default everywhere modern. Google Maps, GPS apps, APIs.
2. Degrees, minutes, seconds (DMS): 40°42'45.99"N 74°00'21.51"WOld-school nautical and aviation format.
3. Degrees and decimal minutes (DDM): 40°42.766'N 74°00.358'WCommon on marine GPS units.

How many decimal places do you actually need?

Each extra decimal in DD format divides your uncertainty by 10:

For most everyday sharing, four decimals is plenty. Posting your home address publicly? Two or three decimals coarsens you to the neighbourhood without giving away the doorway.

A few common stumbles

Is the negative sign on latitude or longitude?

Negative latitude = south of the equator. Negative longitude = west of Greenwich.

What about altitude?

Latitude and longitude pin you to a spot on the surface. Height is a separate value — altitude or elevation — measured in meters above mean sea level. GPS receivers report it in a separate field.

What does “WGS-84” mean?

The global coordinate system virtually every modern GPS, map, and phone uses. Unless you’re a surveyor working with a national grid, WGS-84 is the only one you’ll meet.

Coordinates worth memorising

• 0°, 0° — the intersection of the equator and prime meridian, in the Atlantic off the coast of Ghana. Nicknamed “Null Island”; not actually an island. If you ever see an app place something there, it’s a bug — somebody set lat and lon to zero as a default.
• Eiffel Tower: 48.8584, 2.2945
• Statue of Liberty: 40.6892, −74.0445
• Sydney Opera House: −33.8568, 151.2153
• Mount Everest summit: 27.9881, 86.9250
• North Pole: 90.0, undefined longitude (all meridians meet)
• South Pole: −90.0, undefined longitude

Three edge cases that break poorly-written software

• The antimeridian (longitude ±180°).Where east meets west in the Pacific. A great-circle line from Alaska to Vladivostok crosses ±180°, but naive code treating longitude as a flat number draws the line all the way around the world the other way. You can spot the bug whenever a flight-tracker map shows planes flying through Africa to cross the Pacific.
• The poles (latitude ±90°). Longitude is meaningless here. Distance formulas that assume rectangular coordinates fall apart. Real-world relevance: weather forecasting at McMurdo, GPS-guided drones over Arctic ice.
• West-positive longitude. Some legacy databases (pre-1980s NOAA, for instance) use west-positive instead of today’s east-positive convention. Loading directly into Google Maps reflects every point horizontally.

Distance between two coordinates

How far apart are two latitude–longitude pairs? You can’t use Pythagoras because the Earth is round. The Haversine formula gives the great-circle distance — the shortest path across the sphere’s surface — accurate to within ~0.5% for any pair of points on Earth. For most everyday cases (driving estimates, real-estate copy, flight planning), it’s plenty. For long-distance survey accuracy, the Vincenty formula accounts for Earth’s actual ellipsoid shape and is good to a few millimeters. Both are one-liners in any modern programming language; the distance calculator on this site uses Haversine.

Read your own coordinates

Open the My Location tool and you’ll see your own latitude and longitude in decimal degrees, with six decimals of precision, plus a live map pin. For the raw coordinate display without the address lookup, the GPS Coordinates page does the same job. Worth doing once just to anchor what the numbers feel like for the place you’re sitting in.

If you want to watch the coordinates update as you move — a good way to internalise how small a 0.0001° change actually is in the real world — the Live Location tracker streams a fresh fix every second or two.

Frequently asked questions