how many degrees longitude are between the prime meridian and international dateline?

There are 180 degrees of longitude between the Prime Meridian and the International Date Line. The Prime Meridian is defined as 0° longitude, running through Greenwich, England, and it divides Earth into the eastern and western hemispheres. The International Date Line is based on the antimeridian at 180° longitude, roughly opposite the Prime Meridian on the globe. Since longitude is measured in degrees around a full 360° circle, the point exactly halfway around from 0° is 180°, so the angular distance between the Prime Meridian and the International Date Line is 180° of longitude.