Convert Earth's Polar Radius to Earth's Equatorial Radius
Convert earth's polar radii to earth's equatorial radii instantly. 1 earth's polar radius = 0.9966471401 earth's equatorial radius — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Earth's Equatorial Radius to Earth's Polar Radius converter for the reverse conversion.
Units explained
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.
Earth's Equatorial Radius
Earth's equatorial radius is the distance from the planet's center to its surface at the equator, defined as exactly 6,378,137 meters by the WGS84 geodetic reference system.
The WGS84 (World Geodetic System 1984) defines Earth's reference ellipsoid for use in GPS and global cartography. The 6,378,137 m equatorial value was determined through satellite and ground geodetic measurements consolidated in 1984.
WGS84's equatorial radius is the standard reference for GPS, satellite imagery, geographic information systems, and aviation navigation. It defines the 'a' parameter of Earth's reference ellipsoid in coordinate transformations.
WGS84 reference ellipsoid adopted in 1984 by the US Department of Defense; subsequently adopted globally for GPS and civilian geodesy.
Earth's Polar Radius to Earth's Equatorial Radius conversion formula
The relationship between earth's polar radii and earth's equatorial radii:
To convert earth's polar radii to earth's equatorial radii, multiply the value in earth's polar radii by 0.9966471401. To reverse, multiply earth's equatorial radii by 1.0033641394.
How to use this converter
Type a value into the calculator. The result in earth's equatorial 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 Equatorial Radius to Earth's Polar Radius converter for the reverse direction.
Step-by-step: convert earth's polar radii to earth's equatorial radii
- Write down the value in earth's polar radii (R⊕,p).
- Multiply that value by the factor 0.9966471401.
- The product is the equivalent value in earth's equatorial radii (R⊕,eq).
- To reverse, multiply the earth's equatorial radius value by 1.0033641394.
Worked examples
Example 1 — Convert 1 R⊕,p to R⊕,eq:
1 × 0.9966471401 = 0.9966471401 R⊕,eq
Example 2 — Convert 100 R⊕,p to R⊕,eq:
100 × 0.9966471401 = 99.6647140066 R⊕,eq
Earth's Polar Radius to Earth's Equatorial Radius conversion table
Standard reference values for converting earth's polar radii to earth's equatorial radii:
| Earth's Polar Radius [R⊕,p] | Earth's Equatorial Radius [R⊕,eq] |
|---|---|
| 0.01 | 0.0099664714 |
| 0.1 | 0.099664714 |
| 1 | 0.9966471401 |
| 2 | 1.9932942801 |
| 3 | 2.9899414202 |
| 4 | 3.9865885603 |
| 5 | 4.9832357003 |
| 10 | 9.9664714007 |
| 20 | 19.9329428013 |
| 30 | 29.899414202 |
| 40 | 39.8658856026 |
| 50 | 49.8323570033 |
| 100 | 99.6647140066 |
| 500 | 498.3235700331 |
| 1000 | 996.6471400661 |
Frequently asked questions
How many earth's equatorial radii is 1 earth's polar radius?
How do I convert earth's polar radii to earth's equatorial radii?
How do I convert earth's equatorial radii back to earth's polar radii?
How many earth's equatorial radii is 100 earth's polar radii?
Popular length unit conversions
Convert Earth's Polar Radius to other length units
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Metric / SI (4 units)
Imperial / US Customary (4 units)
Astronomical (8 units)
Sources & references
Conversion factor (1 R⊕,p = 0.9966471401 R⊕,eq) 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.