The speed of light in a vacuum is exactly 299,792,458 meters per second. In miles per hour, this is approximately 670,616,629 mph. This value is a universal physical constant and represents the maximum speed at which all energy, matter, and information can travel in the universe
. To summarize:
- Speed of light in vacuum: 299,792,458 meters per second (exact)
- Speed of light in miles per hour: about 670,616,629 mph (approximately)
This speed is exact because the meter is defined based on the distance light travels in a fraction of a second. Light travels about 186,000 miles per second, which translates to roughly 671 million miles per hour
. If you were to travel at the speed of light, you could circle the Earth more than 7 times in one second
. Thus, the speed of light in mph is about 670.6 million miles per hour.
