Light-Years to Miles Converter
Enter a distance in light-years to see how many miles it represents — or start from miles and get the distance in light-years for astronomy and science communication.
1 ly ≈ 5.878625 × 10¹² miles
Supports scientific notation (e.g. 5.9e12)
We use the IAU-consistent relationship: 1 ly = 9.4607304725808 × 10¹⁵ m, converted to miles → 5.878625 × 10¹² mi.
Conversion formula
miles = light-years × 5.878625 × 10¹²
light-years = miles ÷ 5.878625 × 10¹²
1 ly = 5,878,625,000,000 mi (approx.)
Because these numbers are huge, we allow scientific notation in the miles field. This makes it usable for multi-light-year distances to exoplanets and galactic objects.
Example: Proxima Centauri
Proxima Centauri is about 4.2465 ly from Earth.
miles = 4.2465 × 5.878625 × 10¹² ≈ 2.497 × 10¹³ miles
That’s about 24,970,000,000,000 miles — much easier to express in light-years.
Light-years → miles reference
| Light-years (ly) | Miles (mi) |
|---|
Rounded to 3 significant figures.
What is a light-year?
A light-year is the distance that light travels in one year in vacuum. It is a unit of distance, not time. Because light travels at about 299,792 km/s, in one year it covers almost 9.46 trillion kilometers — or about 5.88 trillion miles.
Why convert to miles?
In outreach and education in the U.S., miles are often more intuitive than kilometers. This tool turns an abstract “4.2 light-years” into a concrete number in miles.
FAQ
1. Why do I see slightly different numbers on different sites?
Different sources may round the speed of light or the length of a year slightly differently. We’re using a high-precision value aligned with astronomical standards, so small variations (at the 5th–6th digit) are normal.
2. Can I convert kilometers too?
Yes: 1 ly = 9.4607304725808 × 10¹² km. You can get miles here and multiply by 1.609344 for km, or use the dedicated ly → km tool.