Convert Kilometer to Sun's Radius
Convert kilometers to sun's radii instantly. 1 kilometer = 1.437401e-6 sun's radius — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Sun's Radius to Kilometer converter for the reverse conversion.
Units explained
Kilometer
A kilometer is a metric unit of length equal to one thousand meters. It is the standard unit for measuring road distances, geographic distances, and other large-scale measurements in metric countries.
The kilometer was defined alongside the meter in 1795 using the standard SI prefix kilo- (from Greek chilioi, "thousand"), denoting one thousand units.
Kilometers are used worldwide (except the United States and a few others) for road signage, geographic distance, athletic events, and scientific distances at planetary scale. Speed limits in most countries are given in km/h.
Adopted 1795 in France as part of the original metric system; the kilometer became the global standard for road and geographic distance through the 19th and 20th century metric adoption.
Sun's Radius
The Sun's radius is approximately 695,700 km (6.957×10⁸ m), defined as the IAU 2015 nominal solar radius for use in stellar physics and exoplanet research.
The IAU (International Astronomical Union) Resolution B3 in 2015 defined a nominal solar radius of exactly 6.957×10⁸ m to serve as a stable reference, independent of actual measurement-uncertainty variations in the real Sun.
Solar radii are used in stellar physics, exoplanet characterisation, and any context where a star's size is expressed relative to the Sun. Most stellar radius measurements are quoted in solar-radius units rather than meters.
Defined exactly at 6.957×10⁸ m by IAU Resolution B3 in 2015.
Kilometer to Sun's Radius conversion formula
The relationship between kilometers and sun's radii:
To convert kilometers to sun's radii, multiply the value in kilometers by 1.437401e-6. To reverse, multiply sun's radii by 695700.
How to use this converter
Type a value into the calculator. The result in sun's radii updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Sun's Radius to Kilometer converter for the reverse direction.
Step-by-step: convert kilometers to sun's radii
- Write down the value in kilometers (km).
- Multiply that value by the factor 1.437401e-6.
- The product is the equivalent value in sun's radii (R☉).
- To reverse, multiply the sun's radius value by 695700.
Worked examples
Example 1 — Convert 1 km to R☉:
1 × 1.437401e-6 = 1.437401e-6 R☉
Example 2 — Convert 100 km to R☉:
100 × 1.437401e-6 = 0.0001437401 R☉
Real-world example — Coastal cruise distances
A 10-kilometer coastal sailing route converts to a different value in sun's radii — useful for cruise operators who switch between maritime, aviation, and road-distance units depending on the leg of the trip.
10 km × 1.437401e-6 = 1.437401e-5 R☉
Real-world example — Road-sign distances across systems
A 100-kilometer road sign converts cleanly into sun's radii — exactly the conversion drivers planning trips abroad rely on when reading road signs in a different measurement system.
100 km × 1.437401e-6 = 0.0001437401 R☉
Real-world example — Endurance race distances
A 50-kilometer cycling or running race converts to a recognizable distance in sun's radii. Endurance athletes coming from a different measurement system use this conversion to compare training plans across regions.
50 km × 1.437401e-6 = 7.187006e-5 R☉
Kilometer to Sun's Radius conversion table
Standard reference values for converting kilometers to sun's radii:
| Kilometer [km] | Sun's Radius [R☉] |
|---|---|
| 0.01 | 1.437401e-8 |
| 0.1 | 1.437401e-7 |
| 1 | 1.437401e-6 |
| 2 | 2.874802e-6 |
| 3 | 4.312204e-6 |
| 4 | 5.749605e-6 |
| 5 | 7.187006e-6 |
| 10 | 1.437401e-5 |
| 20 | 2.874802e-5 |
| 30 | 4.312204e-5 |
| 40 | 5.749605e-5 |
| 50 | 7.187006e-5 |
| 100 | 0.0001437401 |
| 500 | 0.0007187006 |
| 1000 | 0.0014374012 |
Frequently asked questions
How many sun's radii is 1 kilometer?
How do I convert kilometers to sun's radii?
How do I convert sun's radii back to kilometers?
How many sun's radii is 100 kilometers?
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Metric / SI (17 units)
Imperial / US Customary (27 units)
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Astronomical (9 units)
Atomic / Physics (6 units)
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Sources & references
Conversion factor (1 km = 1.437401e-6 R☉) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.