Convert Kilometer to Earth's Polar Radius
Convert kilometers to earth's polar radii instantly. 1 kilometer = 0.000157313 earth's polar radius — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Earth's Polar 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.
Earth's Polar Radius
Earth's polar radius is the distance from the planet's center to either pole, approximately 6,356,752 meters under the WGS84 geodetic reference system. The polar radius is about 21 km shorter than the equatorial radius due to Earth's oblate spheroid shape.
Derived from WGS84's flattening parameter (f ≈ 1/298.257); the difference from the equatorial radius is the geometric signature of Earth's rotational oblateness.
Earth's polar radius is used in geodesy, satellite-orbit calculations, and global cartography. Together with the equatorial radius it defines Earth's reference ellipsoid in WGS84.
Derived from the WGS84 reference ellipsoid adopted in 1984; the value is computed from the equatorial radius minus the oblateness.
Kilometer to Earth's Polar Radius conversion formula
The relationship between kilometers and earth's polar radii:
To convert kilometers to earth's polar radii, multiply the value in kilometers by 0.000157313. To reverse, multiply earth's polar radii by 6356.752.
How to use this converter
Type a value into the calculator. The result in earth's polar 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 Earth's Polar Radius to Kilometer converter for the reverse direction.
Step-by-step: convert kilometers to earth's polar radii
- Write down the value in kilometers (km).
- Multiply that value by the factor 0.000157313.
- The product is the equivalent value in earth's polar radii (R⊕,p).
- To reverse, multiply the earth's polar radius value by 6356.752.
Worked examples
Example 1 — Convert 1 km to R⊕,p:
1 × 0.000157313 = 0.000157313 R⊕,p
Example 2 — Convert 100 km to R⊕,p:
100 × 0.000157313 = 0.0157313043 R⊕,p
Real-world example — Coastal cruise distances
A 10-kilometer coastal sailing route converts to a different value in earth's polar radii — useful for cruise operators who switch between maritime, aviation, and road-distance units depending on the leg of the trip.
10 km × 0.000157313 = 0.0015731304 R⊕,p
Real-world example — Road-sign distances across systems
A 100-kilometer road sign converts cleanly into earth's polar radii — exactly the conversion drivers planning trips abroad rely on when reading road signs in a different measurement system.
100 km × 0.000157313 = 0.0157313043 R⊕,p
Real-world example — Endurance race distances
A 50-kilometer cycling or running race converts to a recognizable distance in earth's polar radii. Endurance athletes coming from a different measurement system use this conversion to compare training plans across regions.
50 km × 0.000157313 = 0.0078656521 R⊕,p
Kilometer to Earth's Polar Radius conversion table
Standard reference values for converting kilometers to earth's polar radii:
| Kilometer [km] | Earth's Polar Radius [R⊕,p] |
|---|---|
| 0.01 | 1.57313e-6 |
| 0.1 | 1.57313e-5 |
| 1 | 0.000157313 |
| 2 | 0.0003146261 |
| 3 | 0.0004719391 |
| 4 | 0.0006292522 |
| 5 | 0.0007865652 |
| 10 | 0.0015731304 |
| 20 | 0.0031462609 |
| 30 | 0.0047193913 |
| 40 | 0.0062925217 |
| 50 | 0.0078656521 |
| 100 | 0.0157313043 |
| 500 | 0.0786565214 |
| 1000 | 0.1573130429 |
Frequently asked questions
How many earth's polar radii is 1 kilometer?
How do I convert kilometers to earth's polar radii?
How do I convert earth's polar radii back to kilometers?
How many earth's polar radii is 100 kilometers?
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Sources & references
Conversion factor (1 km = 0.000157313 R⊕,p) 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.