Light is fast but the universe is vast, so even light takes real time to cross it, and that delay means you always see distant objects as they were in the past. Light travels almost three hundred thousand kilometers every second, covering the Earth to Moon gap in just over a second and the Earth to Sun gap in about eight minutes. This calculator converts a distance into the time light needs to traverse it, and converts a light travel time back into a distance in kilometers, miles and astronomical units. Pick your distance unit and it does the rest, so you can grasp just how far a light year really is. Everything runs in your browser instantly.
Light is fast but the universe is vast, so even light takes real time to cross it, and that delay means you always see distant objects as they were in the past. Light travels almost three hundred thousand kilometers every second, covering the Earth to Moon gap in just over a second and the Earth to Sun gap in about eight minutes.
Yes. Light Travel Time Calculator is completely free, with no sign-up and no usage limits.
Yes. Light Travel Time Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Light Travel Time Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.