Skip to content
Astronomy Calculators

Light Travel Time Calculator

Verified formula Updated Jun 2026 Private — runs on your device

Enter details
km
Verified formula Private

Light travel time

8.32

In seconds
499.0

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Light Travel Time Calculator

The Light Travel Time Calculator works out your light travel time, along with 1 related figure in an instant. Enter distance and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the distance.
  2. Read off your light travel time, together with in seconds — the calculator updates automatically, with no button to press.

Formula

The Light Travel Time Calculator uses the formula:

Light travel time = Distance ÷ 299792.458 ÷ 60

Worked example

For example, with distance of 149,600,000 km, the light travel time is 8.32.

Inputs used
Distance 149,600,000 km
Results
Light travel time 8.32
In seconds 499.0

Results are estimates for educational use, not professional advice.

Frequently asked questions

Divide the distance in km by the speed of light, 299,792 km/s. Sunlight crosses the 149.6 million km to Earth in about 8.3 minutes.

In a vacuum, light travels at about 299,792 kilometres per second, the fastest speed possible.

It is the distance light travels in one minute, about 18 million km. The Sun is roughly 8.3 light-minutes away.

Because light takes time, we see distant objects as they were in the past — looking out in space is looking back in time.

The Light Travel Time Calculator uses the formula: Light travel time = Distance ÷ 299792.458 ÷ 60. For example, with distance of 149,600,000 km, the light travel time is 8.32.

Enter the distance. Read off your light travel time, together with in seconds — the calculator updates automatically, with no button to press.

Related calculators