Light Year Conversion

The Light Year Conversion helps you convert distances expressed in light years into more familiar units like kilometers, miles, astronomical units (AU), Earth radii, and more. A light year is the distance light travels in one year — approximately 5.88 trillion miles or 9.46 trillion kilometers. It’s a useful unit for describing astronomical distances, such as the distance between stars and galaxies.

This tool is especially useful for students, researchers, astronomers, and science enthusiasts who need quick, accurate conversions without needing to memorize astronomical constants.

With a single input — the number of light years — this tool provides real-time conversions across multiple unit systems:

• Metric: kilometers, meters, and decimeters.
• Imperial/US: miles, feet, inches, yards, and kilofeet.
• Astronomical: Earth radii (R🜨), Sun radii (R☉), astronomical units (AU), mega light years (Mly), and mega parsecs (Mpc).

All units are available in simple dropdowns that let you select your preferred output. Once selected, the calculator multiplies your light year value by a pre-set constant for that unit — no need for manual formulas or external tools.

Whether you're trying to grasp how far Proxima Centauri is or convert a cosmic scale for your physics project, this tool gives you the results instantly. Plus, it's designed to mimic the simplicity of our other NGDrives conversion tools — clean interface, mobile-friendly layout, and instant feedback as you type.

If you're curious about the science behind the numbers, be sure to also check out our Speed of Light Calculator and Light Year Calculator to dive deeper.

Converting the distance of stars, galaxies, and the universe into human-understandable numbers might sound cosmic — but this calculator makes it a breeze. Here’s how it all fits together:

What Is a Light Year, Really?

A light year isn’t time — it’s distance. It’s how far light travels in a year:

1 light year = 9.46 trillion kilometers (5.88 trillion miles)
That’s 63,241 times the Earth-Sun distance!

When distances are too big for everyday units, astronomers rely on light years to make the vastness of space more measurable.

From Light Years to Kilometers or Miles

Want to know how many kilometers or miles are in a few light years? Just multiply:

• 1 light year ≈ 9.46 trillion kilometers  e.g., 2 ly × 9.46 trillion = 18.92 trillion km

• 1 light year ≈ 5.88 trillion miles  e.g., 3 ly × 5.88 trillion = 17.64 trillion miles

Into Astronomical Units (AU)

An astronomical unit (AU) is the average distance from Earth to the Sun: 1 AU = ~150 million kilometers

To convert light years to AUs:

1 light year ≈ 63,241 AU
e.g., 5 ly × 63,241 = 316,205 AU

Perfect for solar system-scale calculations.

More Available Units::

• Earth Radii (R🜨) – Great for comparing planetary sizes
• Sun Radii (R☉) – Used for giant stars and stellar distances
• Megaparsecs (Mpc) – 1 Mpc = ~3.26 million light years
• Mega Light Years (Mly) – For galaxy clusters and beyond

These massive units help us describe the universe at its most epic scale.

With this calculator, you don’t need to memorize formulas or do the math manually. Just:

• Enter a value in light years
• Pick your target unit
• Instantly get your result across multiple formats — even obscure units like Sun radii or Mpc

If you encounter any issues or have suggestions for improvements, please report them using the form below.