How fast is the speed of light? In miles per hour?

6 Answers
my question: how fast is the speed of light? in miles per hour?, please. thanks in advance

Hi Weskil76

The speed of light is approximately 299 792 458 meters per second. This is approximately 670 616 629 miles per hour.

Curiously enough the official SI definition for a meter is the distance light travels in a perfect vacuum over the course of one 299 792 458th of a second. So we define meters in terms of the speed of light, then should we measure the speed of light in vacuo we measure it using the meter, a related SI unit, or an imperial unit (which are now also fully defined in terms of the metric system...i.e., the meter!).

So essentially, we're measuring the speed of light in terms of the speed of light, which in turn is defined by...yes that's right, the speed of light...and so on, and so on, ad nauseum, ad infinitum!

But whatever.

Thanks for posting your inquiry!


According to Sir Albert Einstein, light speed is a universal constant and is accepted by every scientist because up until now there are no particles, molecules or matter that break the speed of light.
In metric system, light travels at a speed of 300,000,000 meters per second or in scientific notation it is 3x10^8 m/s. In miles per hour that is 671,080,887.
If you want the exact conversion, using 299,792,458 meters per second, the equivalent miles per hour is 670,616,629.4


The speed of light has been defined as a physical constant. It has been defined as 186,000 miles per second. This comes to 11,160,000 miles per minute. This comes to 669,600,000 miles per hour. This comes to 16,070,400,000 miles per day. This comes to 5,869,713,600,000 miles per year. The terms used are a Light /Second, A Light /Minute, A Light/ Hour, A Light /Day, A light /year.


Light travels at a constant of 186,000 miles per second.


The sped of light in mph is 670,616,629.4


The speed of light is 670,616,640mph