To convert nautical miles to astronomical units, multiply by 1.237985535e-08. That factor is the whole relationship: both units measure length, so the conversion is a proportion with no offset and no substance-specific constant.
Exactly 149,597,870,700 metres — the Earth–Sun distance, and the natural ruler for the solar system. Exactly 1,852 metres — one minute of latitude, the basis of marine and air navigation.
The mil and the millimetre are not the same thing and are out by a factor of about forty. A mil is one thousandth of an inch — 0.0254 mm — and a spec sheet that quotes film thickness in mils means the small unit. British drawings write the same size as "thou". The tables underneath give both a plain step-by-step lookup and a list of real quantities expressed in astronomical units, so you can sanity-check whether your answer is a plausible size.
The formula
nautical miles- The amount you are converting, in nautical miles
1.23798553504e-08- The exact number of astronomical units in one nautical mile
astronomical units- The converted result
How it works, step by step
- Enter the value in nautical miles.
- It is multiplied by 1.23798553504e-08, the exact factor between the two units.
- The answer is shown in astronomical units, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
Earth’s diameter: 6880 nmi in astronomical units
Earth’s diameter comes to about 6880 nmi. Multiplying by the factor: 6880 × 1.23799e-08 = 8.51734e-05 AU. Dividing the answer back by 1.23799e-08 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
The Eiffel Tower: 0.178 nmi in astronomical units
At 0.178 nmi (the eiffel tower), the same quantity in astronomical units is 0.178 × 1.23799e-08 = 2.20361e-09 AU. One nautical mile is 1.23799e-08 astronomical units, so the numbers shrink as expected.
How to read your score
Frequently asked questions
How many astronomical units are in one nautical mile?
Exactly 1.23798553504e-08. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert nautical miles to astronomical units?
astronomical units = nautical miles × 1.23798553504e-08. Reversed, nautical miles = astronomical units ÷ 1.23798553504e-08, which is the same as multiplying by 80,776,388.067.
Which is the bigger unit, the nautical mile or the astronomical unit?
The astronomical unit. One nautical mile is only 1.23799e-08 of a astronomical unit, so it takes 8.07764e+07 nautical miles to make one astronomical unit.
What does this quantity actually measure?
Both units measure length. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a nautical mile?
Exactly 1,852 metres — one minute of latitude, the basis of marine and air navigation.
What is a astronomical unit?
Exactly 149,597,870,700 metres — the Earth–Sun distance, and the natural ruler for the solar system.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do nmi to AU in my head?
Plenty of people do this in their head: divide by 80000000.000000 instead of using the exact factor 1.2380e-08. At 100 that shortcut gives 0.000001 astronomical units, off by 1.2014e-08 astronomical units or about 0.97%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Nautical Miles to astronomical units reference tables
| Nautical Miles | Astronomical Units |
|---|---|
| 0.5 nmi | 6.18993e-09 AU |
| 1 nmi | 1.23799e-08 AU |
| 2 nmi | 2.47597e-08 AU |
| 3 nmi | 3.71396e-08 AU |
| 5 nmi | 6.18993e-08 AU |
| 10 nmi | 1.23799e-07 AU |
| 20 nmi | 2.47597e-07 AU |
| 25 nmi | 3.09496e-07 AU |
| 50 nmi | 6.18993e-07 AU |
| 75 nmi | 9.28489e-07 AU |
| 100 nmi | 1.23799e-06 AU |
| 250 nmi | 3.09496e-06 AU |
| 500 nmi | 6.18993e-06 AU |
| 1000 nmi | 1.23799e-05 AU |
| 5000 nmi | 6.18993e-05 AU |
Exact factor: 1 nautical mile = 1.23798553504e-08 astronomical units.
| Quantity | nmi | AU |
|---|---|---|
| A credit card’s long edge | 4.622e-05 nmi | 5.722e-13 AU |
| A door height | 0.001097 nmi | 1.358e-11 AU |
| An Olympic pool | 0.027 nmi | 3.342e-10 AU |
| The Eiffel Tower | 0.1782 nmi | 2.206e-09 AU |
| A marathon | 22.78 nmi | 2.821e-07 AU |
| Earth’s diameter | 6880 nmi | 8.518e-05 AU |
Published reference values, converted with the same factor this page uses.