Understanding Light Year Conversions

A light year is the distance that light travels in one year in a vacuum. It's approximately 9.46 trillion kilometers (5.88 trillion miles). This unit is essential in astronomy for measuring vast interstellar distances.

How to Use This Converter

Enter a numerical value in the input field
Select the unit you're converting from
Select the unit you want to convert to
View the instant conversion result
Use the swap button to reverse the units

Reference Table

Unit	Kilometers	Miles
1 Light Year	9,460,730,472,580.8 km	5,878,625,541,248 mi
1 Kilometer	1 km	0.621371 mi
1 Mile	1.609344 km	1 mi

Practical Examples

The distance to Proxima Centauri is about 4.24 light years (40.14 trillion km or 24.94 trillion miles)
The diameter of the Milky Way is approximately 100,000 light years
The Andromeda Galaxy is 2.5 million light years away

Important Notes

Conversions use the International Astronomical Union's definition of 1 light year = 9,460,730,472,580.8 km exactly. Mile conversions use the international mile definition (1 mile = 1.609344 km). Results are rounded for display but calculations use full precision.

Frequently Asked Questions

Why is a light year used instead of kilometers or miles?

Astronomical distances are so vast that using kilometers or miles would result in inconveniently large numbers. Light years provide a more manageable scale for interstellar measurements.

Is a light year a unit of time or distance?

Despite containing "year" in its name, a light year is exclusively a unit of distance, not time. It represents the distance light travels in one year.

How accurate are these conversions?

The conversion from light years to kilometers is based on the IAU's exact definition. Mile conversions use the international standard definition. Calculations maintain full precision with results rounded for display.

Light Year Converter

Result

Common Light Year Conversions

Menu

Light Year Converter to Kilometers and Miles

AI Assistant

Was this tool helpful?