# Light-years to Nautical Miles (ly to nmi)

Source: https://www.unitconvertercalculator.com/length/light-years-to-nautical-miles/

**1 ly = 5108385784330.9 nmi**

One light-year equals approximately 5.108 x 1012 nautical miles (about 5.1 trillion NM). The light-year measures interstellar space; the nautical mile (1,852 m) measures sea and air distances. Both are travel units, just at incomparably different scales.

## Formula

Convert Light-years to Nautical Miles

## Conversion Table

| Light-years (ly) | Nautical Miles (nmi) |
|---|---|
| 0.001 ly | 5108385784.3309 nmi |
| 0.01 ly | 51083857843.309 nmi |
| 0.1 ly | 510838578433.09 nmi |
| 0.5 ly | 2554192892165.4 nmi |
| 1 ly | 5108385784330.9 nmi |
| 2 ly | 10216771568662 nmi |
| 4.24 ly | 21659555725563 nmi |
| 5 ly | 25541928921654 nmi |
| 8.6 ly | 43932117745246 nmi |
| 10 ly | 51083857843309 nmi |
| 50 ly | 2.5541928921654E+14 nmi |
| 100 ly | 5.1083857843309E+14 nmi |
| 1000 ly | 5.1083857843309E+15 nmi |
| 100000 ly | 5.1083857843309E+17 nmi |

## Units

### Light-year (ly)

The distance light travels in one Julian year (365.25 days) in vacuum. Exactly 9,460,730,472,580,800 meters. Used for interstellar distances.

### Nautical Mile (nmi)

Exactly 1852 meters by international agreement. Based on one minute of arc of latitude at the Earth's surface. The standard unit for maritime and air navigation.

## Background

Light travels about 161,875 nautical miles per second. Proxima Centauri is about 21.66 trillion NM away. The longest ocean voyage (circumnavigation at about 21,600 NM) is 2.36 x 10-9 light-years. The ocean is a puddle compared to interstellar space.

## Good to Know

The nautical mile was defined by the Earth (1 arcminute of latitude). The light-year was defined by physics (distance light travels in a year). One is planetary; the other is cosmic. Both measure how far humans travel - just at very different ambition levels.

## FAQ

### How many nautical miles are in 1 light-year?

One light-year contains approximately 5.108 x 1012 NM (about 5.1 trillion).

### How fast does light travel in knots?

Light travels at approximately 582,749,918 knots (NM/hour). That is about 583 million knots.

### How long would a ship take to travel 1 light-year?

At 20 knots (typical cargo ship), covering 1 light-year would take about 29.1 million years. Your cargo would not arrive fresh.

## Non-Frequently Asked Questions

### How many circumnavigations of Earth equal 1 light-year?

Earth's circumference is about 21,600 NM. One light-year is about 5.1 trillion NM. That is about 236 million laps around Earth. Magellan's crew took 3 years for one. You would need 708 million years. The Earth might not be there when you finish.

### How fast is light in knots?

About 583 million knots. The fastest ship ever (USS Enterprise aircraft carrier at trials) made about 35 knots. Light is 16.6 million times faster than a nuclear-powered aircraft carrier. Physics always wins the speed competition.

### If Columbus sailed at 4 knots toward Proxima Centauri, when would he arrive?

At 4 knots, Columbus would cover 1 light-year in about 146 million years. To reach Proxima Centauri (4.24 ly), he would need 619 million years. Columbus left Spain in 1492. He would arrive around the year 619,001,492. Mark your calendar.

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## See Also

- [Nautical Miles to Light-years](https://www.unitconvertercalculator.com/length/nautical-miles-to-light-years/)