A light-year is the distance light travels in a Julian year.
Light-years to Meters Converter — ly to m
Convert Light-year (ly) to Meter (m) using the exact conversion factor (1 light-year = 9.46073e+15 meter). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Light-years to Meters converter
Converter
Length Converter
Convert SI, imperial, US customary, astronomical, scientific, and historical length units.
Context values
Some unit families need one extra value for a physically accurate result.
The meter is the SI base unit of length.
Result = input x 9.46073047e+15 / 1.
Length uses the meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Light-years to Meters
Light-year and Meter both measure length. Light-year is typically associated with used internationally in astronomy and popular science for interstellar distances., while Meter is typically associated with standard length unit worldwide except the US.
Formula
meters = light-years × 9.46073e+15
This factor comes from each unit's defined relationship to the category's base unit: 1 light-year equals 9.46073e+15 base units, and 1 meter equals 1 base unit, so dividing one by the other gives the direct light-year-to-meter factor of 9.46073e+15.
Simple example
1 ly × 9.46073e+15 = 9.46073e+15 m
1 light-year = 9.46073e+15 meters.
Real-world example
10 ly × 9.46073e+15 = 9.46073e+16 m
10 light-years = 9.46073e+16 meters.
Conversion table
| Light-year (ly) | Meter (m) |
|---|---|
| 1 ly | 9.46073e+15 m |
| 5 ly | 4.730365e+16 m |
| 10 ly | 9.46073e+16 m |
| 21.0975 ly | 1.995978e+17 m |
| 42.195 ly | 3.991955e+17 m |
| 100 ly | 9.46073e+17 m |
Reverse conversion: Meter to Light-year
9.46073e+15 m × 1.057001e-16 = 0.99999995 ly
9.46073e+15 meters = 0.99999995 light-years.
light-years = meters × 1.057001e-16
For a page dedicated to this direction, see Meter to Light-year.
Light-year vs. Meter
| Aspect | Light-year | Meter |
|---|---|---|
| Family | Non-SI unit (astronomical) | SI base unit |
| Typical use | Measuring distances to stars and galaxies | Universal scientific and everyday length measurement outside the US |
| Where it's used | Used internationally in astronomy and popular science for interstellar distances. | Standard length unit worldwide except the US |
Understanding the Light-year
Light-year (ly) measures distance. A light-year is the distance light travels in one Julian year (365.25 days) in vacuum: exactly 9,460,730,472,580,800 meters. It is classified as a Non-SI unit (astronomical).
Where it's used: Used internationally in astronomy and popular science for interstellar distances.
Uses of the Light-year today
- Measuring distances to stars and galaxies
- Popular science communication about the scale of the universe
- Astrophysics research
History of the Light-year
The light-year emerged in 19th-century astronomy as scientists began measuring stellar distances via parallax (Friedrich Bessel's 1838 measurement of 61 Cygni is often cited as the first reliable stellar distance). Expressing these vast distances in light-travel-time became a practical convention, and the unit's value follows directly from the defined speed of light and the length of a Julian year.
Historical origin. Light-year was not the invention of a single named person; it developed through the process described above.
Understanding the Meter
Meter (m) measures distance. The meter is the SI base unit of length, currently defined via the fixed speed of light. It is classified as a SI base unit.
Where it's used: Standard length unit worldwide except the US
Uses of the Meter today
- Universal scientific and everyday length measurement outside the US
- Construction, engineering, and manufacturing internationally
History of the Meter
Defined during the French Revolutionary metric reforms as one ten-millionth of the distance from the North Pole to the Equator, the meter has been redefined several times for precision — a platinum-iridium bar (1889), a krypton-86 wavelength (1960), and since 1983, the distance light travels in 1/299,792,458 of a second.
Historical origin. Meter was not the invention of a single named person; it developed through the process described above.
Light-year — sources
- IAU — Light year definition — Defines the light-year via the Julian year and the speed of light.
Meter — sources
- BIPM — The metre (SI base unit) — Current definition and history of the meter.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many meters are in 1 light-year?
1 light-year equals 9.46073e+15 meters, using the exact defined conversion factor rather than an estimate.
How do I convert light-year to meter?
Multiply the light-year value by 9.46073e+15. The converter above does this instantly to whatever precision you set.
How do I convert meter back to light-year?
Use the reverse factor: 1 meter equals 1.057001e-16 light-years. You can also use the swap control in the converter above to flip the direction instantly.
What is a light-year?
Light-year (ly) measures distance. A light-year is the distance light travels in one Julian year (365.25 days) in vacuum: exactly 9,460,730,472,580,800 meters. It is classified as a Non-SI unit (astronomical).
What is a meter?
Meter (m) measures distance. The meter is the SI base unit of length, currently defined via the fixed speed of light. It is classified as a SI base unit.
Is the light-year to meter conversion exact?
Yes. A light-year is the distance light travels in one Julian year (365.25 days) in vacuum: exactly 9,460,730,472,580,800 meters. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the light-year still used today?
Used internationally in astronomy and popular science for interstellar distances.