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Length

Convert light years to feet

1 ly=3.1039e16ft

Use the converter below to change any light years value into feet instantly — with formula, conversion table, and real-world examples.

3.1039e16

Conversion formula

Forward
feet = light years × 3.1039e16
Reverse
light years = feet × 3.2217e-17

Example: 10 ly × 3.1039e16 = 3.1039e17 ft.

About both units

From

Light Year

ly

A light year is the distance light travels in one Julian year — approximately 9.461 × 10¹⁵ meters, or 63,241 AU. It is used in astronomy to describe distances between stars and galaxies. The nearest star to the Sun, Proxima Centauri, is 4.24 light years away.

Real-world: Proxima Centauri, the nearest star beyond the Sun, is 4.24 ly away. The Milky Way is about 100,000 ly across.
Read full light year reference →
To

Foot

ft

The foot equals 30.48 centimeters exactly and is one of the oldest length units in human history. It is the international aviation standard for altitude — commercial airliners cruise at 35,000 feet. In the US, building dimensions, human height and elevation are all expressed in feet. 1 foot = 12 inches.

Real-world: Airliners cruise at 35,000 ft (10.7 km). Mount Everest is 29,032 ft (8,849 m). A standard US ceiling is 8 ft (2.44 m).
Read full foot reference →

Light Year to Foot conversion table

Common light years to feet values for quick reference.

Light Year (ly)Foot (ft)
1 ly3.1039e16 ft
5 ly1.5520e17 ft
10 ly3.1039e17 ft
25 ly7.7598e17 ft
50 ly1.5520e18 ft
100 ly3.1039e18 ft
250 ly7.7598e18 ft
500 ly1.5520e19 ft
1,000 ly3.1039e19 ft
5,000 ly1.5520e20 ft

Tips & common mistakes

Quick tips

  • The light year is a unit of distance, not time, despite the name.
  • Professional astronomers usually prefer parsecs (1 pc ≈ 3.26 ly) for precision work.
  • Light from the Andromeda galaxy takes 2.5 million years to reach us — we see it as it was 2.5 Myr ago.

Avoid these

  • Confusing light year with light second — light second ≈ 300,000 km.
  • Treating light years as time rather than distance in casual conversation.
  • Using light years for solar-system distances — use astronomical units (AU) instead.

Frequently asked questions

How many feet in a light year?
One light year equals 3.1039e16 feet.
How do I convert light years to feet?
Multiply the light year value by 3.1039e16 to get the equivalent in feet.
What is 100 light years in feet?
100 light years equals 3.1039e18 feet.
Is a light year bigger than a foot?
Yes. 1 light year equals 3.1039e16 feet, so one light year is larger.
How to convert light years to feet without a calculator?
Multiply by 3.1039e16 for a quick estimate; use a calculator for precise results.

Related length conversions

📊 See full comparison matrix →

More from Light Year

ly → m
1 = 9.4607e15 m
ly → km
1 = 9,460,700,000,000 km
ly → cm
1 = 9.4607e17 cm
ly → mm
1 = 9.4607e18 mm
ly → mi
1 = 5,878,606,438,399.75 mi
ly → yd
1 = 1.0346e16 yd
ly → in
1 = 3.7247e17 in
ly → nmi
1 = 5,108,369,330,453.56 nmi

More to Foot

m → ft
1 = 3.28084 ft
km → ft
1 = 3,280.84 ft
cm → ft
1 = 0.03281 ft
mm → ft
1 = 0.003281 ft
mi → ft
1 = 5,280 ft
yd → ft
1 = 3 ft
in → ft
1 = 0.08333 ft
nmi → ft
1 = 6,076.12 ft

Conversions in other categories

WeightKilogram → PoundTemperatureCelsius → FahrenheitVolumeLiter → US GallonAreaSquare Meter → Square FootSpeedKilometer per Hour → Mile per HourEnergyKilojoule → KilocaloriePressureBar → Pound per Square InchPowerKilowatt → Mechanical Horsepower