How Long Is a Degree of Latitude and Longitude?

One degree of latitude is about 111 kilometres on the ground, wherever you are. One degree of longitude is also about 111 km at the equator, but it gets shorter as you move toward the poles and shrinks to zero at the poles themselves. This difference matters whenever you convert coordinate differences into real distances.

Why latitude is steady

Lines of latitude are parallel circles, evenly spaced from the equator to the poles. A full trip from pole to pole covers 180 degrees, and the distance along any meridian is roughly 20,000 km, so each degree is about 111 km. A minute of latitude is about 1.85 km (this is the origin of the nautical mile), and a second is a little over 30 m.

The Earth is slightly flattened, so the true value varies a little between the equator and the poles, but 111 km is accurate enough for estimates.

Why longitude changes

Meridians all start at the North Pole and end at the South Pole. They are furthest apart at the equator and converge as they approach the poles. The ground distance of one degree of longitude is therefore roughly:

111 km multiplied by the cosine of the latitude

Some approximate values:

Latitude	One degree of longitude
0 degrees (equator)	about 111 km
30 degrees	about 96 km
45 degrees	about 79 km
60 degrees	about 56 km
90 degrees (pole)	0 km

Quick distance estimates

Suppose two points differ by 0.01 degrees of latitude. That is about 1.1 km north to south. If they differ by 0.01 degrees of longitude at 45 degrees latitude, that is about 0.79 km east to west. Combine both with the Pythagorean theorem for a short-range estimate. For long distances, or when accuracy matters, use a proper great-circle formula, because a flat approximation breaks down over large areas.

What this means for precision

Because longitude distances vary with latitude, the same number of decimal places gives slightly different precision east to west depending on where you are. Latitude precision stays constant. The decimal places guide turns this into a simple table.

Related reading

• What latitude and longitude are
• Map projections and distortion, which explains why flat maps cannot show these distances evenly
• Bounding boxes, where degree-based sizes come up often