How Long Is a Degree of Latitude?

The short answer

One degree of latitude is about 111 kilometres (69 miles) anywhere on Earth. One degree of longitude is also about 111 km at the equator, but multiply that by the cosine of your latitude as you move away from it: about 85 km at 40°, 56 km at 60°, and zero at the pole, where all the meridians meet.

The full table

Latitude	1° latitude	1° longitude	1″ longitude
0° (equator)	110.574 km	111.319 km	30.9 m
10°	110.608 km	109.639 km	30.5 m
20°	110.704 km	104.647 km	29.1 m
30°	110.852 km	96.486 km	26.8 m
40°	111.035 km	85.394 km	23.7 m
50°	111.229 km	71.696 km	19.9 m
60°	111.412 km	55.800 km	15.5 m
70°	111.562 km	38.187 km	10.6 m
80°	111.660 km	19.393 km	5.4 m
90° (pole)	111.694 km	0 km	0 m

Computed on the WGS84 ellipsoid, the reference shape GPS and web maps use.

Why latitude is not perfectly constant either

Look closely at the latitude column and it grows slightly as you go north: 110.574 km at the equator, 111.694 km at the pole. That 1.1 km spread is the Earth’s flattening showing up. The planet bulges at the equator, so its surface curves more sharply there, and a degree of arc covers correspondingly less ground. Near the poles the surface is flatter, so a degree stretches further.

Anyone who assumes a perfect sphere is therefore off by up to about half a percent. That is negligible for a walking route and very much not negligible for surveying — which is why the ellipsoid exists.

Where the nautical mile comes from

One arc-minute of latitude — a sixtieth of a degree — is the original definition of the nautical mile, which is why it is such a natural unit at sea: one minute of latitude on the chart is one nautical mile of sailing. Because the Earth is not a sphere, that arc-minute is not constant, running from 1,843 m at the equator to 1,862 m at the pole.

The international nautical mile was therefore fixed at exactly 1,852 m — which is the value the arc-minute takes at roughly 45° latitude, splitting the difference. The tidy number in the standard is an average of a quantity that genuinely varies.

How many decimal places do you need?

The practical use of all this is knowing when to stop copying digits. Each decimal place in a coordinate divides the ground distance by ten:

Decimals	Step	On the ground	Enough to identify
1	0.1°	11.1 km	Which country, roughly.
2	0.01°	1.1 km	Which town or district.
3	0.001°	111 m	Which neighbourhood.
4	0.0001°	11.1 m	Which building.
5	0.00001°	1.1 m	Which room, or a parked car.
6	0.000001°	0.11 m	Beyond what consumer GPS can justify.

Figures are for the equator and for latitude anywhere; longitude steps shrink with the cosine, so at 60° each one covers half as much ground. Five decimal places is about the limit of what a phone GPS can honestly support. Anything beyond six is arithmetic noise from whatever produced the number, not information about a place.