Light Year Calculator

What Is a Light Year Calculator?

A light-year is the distance light travels in one year — used because the distances between stars are so vast that kilometers become unwieldy. This calculator finds the actual distance covered for any number of years of light travel.

How to Use This Light Year Calculator

1. Enter the number of years of light travel you want to convert (1 for a standard light-year).
2. Click Calculate to get the distance in kilometers, miles, and astronomical units.

Formula

• Distance = speed of light × time (in seconds)
• 1 year ≈ 365.25 × 24 × 3600 seconds

Worked Example

In 1 year, light travels 299,792.458 km/s × 31,557,600 s ≈ 9.461×10¹² km ≈ 5.879×10¹² miles ≈ 63,241 AU — the standard definition of one light-year.