Latitude vs Longitude: Which Goes Which Way?
Latitude lines run east-west (horizontally) and measure north-south position. Longitude lines run north-south (vertically) and measure east-west position. The Equator is 0° latitude; the Prime Meridian is 0° longitude. Memory trick: latitude lines are like 'ladder' rungs — horizontal steps going up or down.
Which way does latitude go? Which is the Equator? Which lines go through the poles? The latitude-longitude pair is fundamental to navigation, geography, and GPS — and the two are regularly confused. The core distinction: latitude measures how far north or south you are; longitude measures how far east or west you are. The visual confusion comes from the fact that latitude lines run east-west (parallel to the equator) while measuring your north-south position, which seems counterintuitive until you think about it correctly.
Key Differences at a Glance
| Feature | Latitude | Longitude |
|---|---|---|
| What it measures | North-south position | East-west position |
| Direction the lines run | East-west (horizontal on a flat map) | North-south (vertical on a flat map, through both poles) |
| Zero line | The Equator (0°) | The Prime Meridian through Greenwich, UK (0°) |
| Range | 0° (Equator) to 90° N (North Pole) or 90° S (South Pole) | 0° (Prime Meridian) to 180° E or 180° W (International Date Line) |
| Parallel lines? | Yes — all lines of latitude are parallel to each other | No — all lines of longitude converge at the poles |
| Length of lines | Longest at Equator, shortest near poles | All the same length (great circles, half of Earth's circumference) |
| Memory trick | LAT = lAT (flat) lines; like ladder rungs (horizontal) | LONG = LONGer top to bottom; vertical lines |
Latitude: Measuring North and South
Lines of latitude (also called parallels) run east-west parallel to the Equator. The Equator is 0° latitude. Moving north, latitude increases from 0° to 90° at the North Pole. Moving south, it increases from 0° to 90° at the South Pole (written 90°S). Major latitude lines: 23.5°N — the Tropic of Cancer (Sun directly overhead at June solstice). 23.5°S — the Tropic of Capricorn (Sun directly overhead at December solstice). 66.5°N and 66.5°S — the Arctic and Antarctic Circles (boundaries of polar day and night). London is at approximately 51.5°N. New York City is at approximately 40.7°N. Sydney is at approximately 33.9°S.
Longitude: Measuring East and West
Lines of longitude (also called meridians) run north-south from pole to pole. The Prime Meridian, established by international agreement in 1884 to pass through the Royal Observatory in Greenwich, London, is 0° longitude. Moving east from Greenwich, longitude increases to 180°E. Moving west, it increases to 180°W. At 180°, the International Date Line runs roughly north-south through the Pacific Ocean — the place where, crossing it eastward, you move back a calendar day, and crossing it westward, you move forward. Unlike latitude lines (which are all parallel), longitude lines converge at both poles. All meridians are the same length.
GPS and Coordinates
GPS coordinates are given as latitude first, longitude second (the convention 'lat, long'). A location like '51.4778°N, 0.0015°W' describes a point just north of the Equator (51.4° north) and just west of the Prime Meridian (0.0015° west) — the location of the Royal Observatory, Greenwich. Decimal degrees are used in digital mapping; degrees, minutes, and seconds (DMS) are used in traditional navigation. One degree of latitude always represents the same distance (approximately 111 km). One degree of longitude varies with latitude — 111 km at the Equator, converging to 0 at the poles.
Frequently Asked Questions
Which way does latitude go?
Latitude lines run east-west (horizontally on a flat map) but measure your north-south position. The Equator (0°) is the reference; 90°N is the North Pole; 90°S is the South Pole.
Which way does longitude go?
Longitude lines run north-south (vertically on a flat map, through both poles) and measure your east-west position. The Prime Meridian through Greenwich (0°) is the reference; 180° is the International Date Line.
What is the Equator?
The Equator is the line of 0° latitude — the imaginary circle around Earth at equal distance from both poles, dividing the planet into the Northern and Southern Hemispheres.
What is the Prime Meridian?
The Prime Meridian is the line of 0° longitude, running through the Royal Observatory in Greenwich, London. Established by international agreement in 1884, it is the reference point for measuring east-west position.
What is the International Date Line?
An imaginary line at approximately 180° longitude (the opposite side of the Earth from the Prime Meridian) where the calendar date changes. Crossing it eastward moves you back one day; crossing it westward moves you forward one day.
How is GPS location given — latitude first or longitude?
Latitude first, longitude second. The convention is 'lat, long' — so the format is (north-south position, east-west position). For example: 51.48°N, 0.00°W for Greenwich.
What countries does the Equator pass through?
The Equator passes through Ecuador, Colombia, Brazil, São Tomé and Príncipe, Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, Somalia, the Maldives, Indonesia, and Kiribati.
How We Write These Comparisons
SmartAss Facts comparisons are written to be the clearest, most accurate answer to "what is the difference between X and Y?" on the internet. We start from the primary definition — taxonomic, scientific, or linguistic — and work outward to the practical distinctions most people actually need.
Each comparison table row is independently sourced. If a distinction is more nuanced than a table cell allows, the detail appears in the body sections below the table. If you find an error or a meaningful distinction we have omitted, the comparison index includes contact information. Last reviewed: 2026-05-23.
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