This page converts microns into astronomical units using the factor 6.684587122e-18, and shows the reverse figure alongside it. Both units measure length, which is why one number does the whole job.
The older name for a micrometre, still standard in filtration, machining and paint-thickness specifications. Exactly 149,597,870,700 metres — the Earth–Sun distance, and the natural ruler for the solar system.
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
microns- The amount you are converting, in microns
6.68458712227e-18- The exact number of astronomical units in one micron
astronomical units- The converted result
How it works, step by step
- Enter the value in microns.
- It is multiplied by 6.68458712227e-18, 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
A credit card’s long edge: 8.56e+04 micron in astronomical units
Take a credit card’s long edge, roughly 8.56e+04 micron. The conversion is a single multiplication — 8.56e+04 × 6.68459e-18 — giving 5.72201e-13 AU. Because the relationship is proportional, doubling the input doubles the answer to 1.14440e-12 AU.
A door height: 2.03e+06 micron in astronomical units
A door height comes to about 2.03e+06 micron. Multiplying by the factor: 2.03e+06 × 6.68459e-18 = 1.35697e-11 AU. Dividing the answer back by 6.68459e-18 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
How to read your score
Frequently asked questions
How many astronomical units are in one micron?
Exactly 6.68458712227e-18. 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 microns to astronomical units?
astronomical units = microns × 6.68458712227e-18. Reversed, microns = astronomical units ÷ 6.68458712227e-18, which is the same as multiplying by 1.49597870700e+17.
Which is the bigger unit, the micron or the astronomical unit?
The astronomical unit. One micron is only 6.68459e-18 of a astronomical unit, so it takes 1.49598e+17 microns 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 micron?
The older name for a micrometre, still standard in filtration, machining and paint-thickness specifications.
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.
Microns to astronomical units reference tables
| Microns | Astronomical Units |
|---|---|
| 0.5 micron | 3.34229e-18 AU |
| 1 micron | 6.68459e-18 AU |
| 2 micron | 1.33692e-17 AU |
| 3 micron | 2.00538e-17 AU |
| 5 micron | 3.34229e-17 AU |
| 10 micron | 6.68459e-17 AU |
| 20 micron | 1.33692e-16 AU |
| 25 micron | 1.67115e-16 AU |
| 50 micron | 3.34229e-16 AU |
| 75 micron | 5.01344e-16 AU |
| 100 micron | 6.68459e-16 AU |
| 250 micron | 1.67115e-15 AU |
| 500 micron | 3.34229e-15 AU |
| 1000 micron | 6.68459e-15 AU |
| 5000 micron | 3.34229e-14 AU |
Exact factor: 1 micron = 6.68458712227e-18 astronomical units.
| Quantity | micron | AU |
|---|---|---|
| A credit card’s long edge | 8.56e+04 micron | 5.722e-13 AU |
| A door height | 2.032e+06 micron | 1.358e-11 AU |
| An Olympic pool | 5e+07 micron | 3.342e-10 AU |
| The Eiffel Tower | 3.3e+08 micron | 2.206e-09 AU |
| A marathon | 4.22e+10 micron | 2.821e-07 AU |
| Earth’s diameter | 1.274e+13 micron | 8.518e-05 AU |
Published reference values, converted with the same factor this page uses.