✨ Light Year Conversion
Translate light years to intuitive units like kilometers, astronomical units, and light travel times.
Choose the starting unit—light years, astronomical units, kilometers, miles, meters, or nautical miles. The converter reveals how far light travels across different scales.
Enter a non-negative number. Decimals are welcome.
Light Years (ly)
1
Astronomical Units (AU)
63,241.07708427
Kilometers (km)
9,460,730,472,580.8
Miles (mi)
5,878,625,373,183.607
Meters (m)
9,460,730,472,580,800
Nautical Miles (NM)
5,108,385,784,330.886
Light would take 525,960 minutes (8,766 hours) to travel this distance.
That equals 365.25 light days, or 52.18 light weeks.
In months: approximately 12 months of light-speed travel.
How to Use This Calculator
Select your starting unit
Choose whether your measurement is in light years, astronomical units, kilometers, miles, meters, or nautical miles.
Enter the distance
Input the numeric value. The calculator accepts decimal and very large numbers used in astronomy.
Explore the conversions
Review the equivalent distance across all included units, plus how long light would take to travel that far.
Formula
1 light year = 9.4607304725808 × 10¹² km
1 light year = 63,241.077 astronomical units
Light travel time (minutes) = Distance (meters) ÷ 299,792,458 ÷ 60
The converter uses the IAU 2012 definitions for astronomical units and the CODATA value for the speed of light.
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
Light-year conversions help contextualise astronomy data for students, educators, journalists, and space enthusiasts. While scientists frequently use parsecs or astronomical units, everyday readers benefit from more familiar units such as kilometers and miles.
This tool provides both distance-based and time-based interpretations, letting you describe how long light would take to cross vast interstellar gaps. It automatically handles large numbers, so you can focus on storytelling or analysis instead of manual math.
Use the results in planetarium shows, classroom worksheets, sci-fi writing, or mission briefings to bridge the gap between scientific notation and intuitive understanding.
Frequently Asked Questions
What exactly is a light year?
A light year is the distance light travels in vacuum over one Julian year (365.25 days), approximately 9.46 trillion kilometers.
Why include nautical miles?
Space mission planners and navigation specialists sometimes compare distances using nautical miles. Including them keeps the tool versatile.
Are the astronomical unit conversions accurate?
Yes. The calculator uses 1 AU = 149,597,870.7 km, the current IAU standard as of 2012.
Can I convert from kilometers to light years?
Absolutely. Choose kilometers as the starting unit, enter the distance, and read the light-year result in the table.