Exactly how long is a Light Year?

We've all heard that a light year is a measurement of distance not time. Well a light year is as it says on the tin,the distance light travels in a year in a vacuum. Seeing that light travels at 300,000 km (or 186,000 miles) a second, a Light Year is equal to about 5,878,630,000,000 miles or 9,460,730,472,580.8 kilometers.

Ps. The nearest star to our own is Proxima Centuri at 4.3 Light Years away (now I dare you go and convert that to kilometers)