Astronomical Unit Calculator

Use this calculator to convert between astronomical units and kilometers for astronomy, education, and space planning. This page also keeps the formula, examples, FAQs, and references close by so you can check the result with confidence.

What This Astronomical Unit Calculator Helps You Do

1 AU equals 149,597,870.7 kilometers. Review the formula and examples below if you want to see how the result is derived.

This page is meant to give you a fast answer, but it also helps you double-check the math before you make a decision. Start with the inputs that you already know, run the calculation, and then compare the output with the formula, examples, and FAQs below so you can see whether the answer fits the situation you are modeling.

If the result looks off, the usual causes are a unit mismatch, a missing decimal, the wrong scenario, or a value that needs to be entered as a rate instead of a total. The notes on this page are designed to make those checks easy without forcing you to leave the calculator and search for context elsewhere.

  • Use the calculator first for a quick estimate.
  • Use the formula to understand how the result is built.
  • Use the examples to compare common use cases.
  • Use the references when the answer depends on a standard or assumption.

Common Checks

A quick result is useful, but the best result is one that still makes sense when you look at it a second time. If you are comparing scenarios, try changing one input at a time so you can see which variable has the biggest impact on the final answer. That makes it much easier to spot whether the calculation matches your expectations.

It also helps to keep the context of the problem in mind. A calculator can tell you the math, but you still need to decide whether the input represents a total, a rate, an average, or a category-specific assumption. When in doubt, start with a simple example from the page and scale up from there.

  • Check that every unit matches the rest of the problem.
  • Keep rates, totals, and averages separate.
  • Adjust one variable at a time when testing scenarios.
  • Use the smallest realistic input first, then scale upward.

Scenario Planning

This calculator is especially useful when you want a quick answer before you commit time, money, or effort. Try one baseline input set, then change a single number and compare the result so you can see how sensitive the answer is to that variable.

That makes the page useful for more than just arithmetic. It becomes a small decision aid that helps you compare options, test assumptions, and explain the final number with confidence when you need to share it with someone else.

AU
km

Result

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Quick Answer: 1 AU equals 149,597,870.7 kilometers. Review the formula and examples below if you want to see how the result is derived.

How to Calculate Astronomical Unit Calculator

  1. Choose a unit: Pick kilometers or astronomical units as the result.
  2. Enter the distance: Type the known space distance into the matching field.
  3. Convert it: The calculator applies the standard AU relationship.
  4. Use the result: Copy the converted value into your lesson, model, or report.

Astronomical Unit Calculator Formula

kilometers = astronomical units x 149597870.7
Variable Meaning Unit
astronomical units Distance in astronomical units AU
kilometers Distance in kilometers km

Worked Examples

USA - Earth orbit scale
  • Astronomical units: 1

Result: Kilometers = 149,597,870.7 km

One AU is the standard Earth-Sun distance.

UK - Inner solar system
  • Astronomical units: 0.5

Result: Kilometers = 74,798,935.35 km

Half an AU is still a very large distance.

EU - Reverse conversion
  • Kilometers: 300000000

Result: Astronomical units = 2.0054 AU

Kilometers convert back by dividing by the same constant.

GCC - Outer orbit
  • Astronomical units: 30

Result: Kilometers = 4,487,936,121 km

Large AU values are common when discussing the outer solar system.

Astronomical Unit Reference

AU values are helpful for solar system distances.

Range Meaning Action
< 0.5 AU Inner solar system distance Check whether you intended kilometers or miles.
0.5-5 AU Solar system scale Use the converted value for astronomy or education.
5-30 AU Outer solar system scale Keep enough precision for your analysis.
> 30 AU Deep solar system distance Confirm that AU is the right unit for the context.
AU values are helpful for solar system distances.
AU Kilometers Note
0.1 14,959,787.1 Inner solar system scale
1 149,597,870.7 Average Earth-Sun distance
5 747,989,353.5 Outer planet scale
30 4,487,936,121 Far outer solar system

Frequently Asked Questions

One astronomical unit is about 149,597,870.7 kilometers.

Yes. Use the reverse mode and divide by 149,597,870.7.

Yes. It is a distance unit used mainly in astronomy.

Yes. It is ideal for comparing planetary and orbital distances.

Yes. Decimal values are fully supported.
Planning note: This calculator converts distance only. It does not account for orbital eccentricity or time-varying distances.

References

Last reviewed: March 28, 2026