Instant · Precise · Universal
32 units available
6 categories total
To convert inches to cm: multiply by 2.54. To convert cm to inches: divide by 2.54.
1 in = 25.4 mm = 2.54 cm = 1/12 ft = 1/36 yd.
For example, 1 Inch (in) = 3.982354e-9 Earth's Equatorial Radius (R⊕ (eq)).
| Inch (in) | Earth's Equatorial Radius (R⊕ (eq)) |
|---|---|
| 0.1 | 3.982354e-10 |
| 0.5 | 1.991177e-9 |
| 1 | 3.982354e-9 |
| 2 | 7.964708e-9 |
| 5 | 1.991177e-8 |
| 10 | 3.982354e-8 |
| 25 | 9.955885e-8 |
| 50 | 1.991177e-7 |
| 100 | 3.982354e-7 |
| 500 | 0.000001991177047 |
| 1000 | 0.000003982354095 |
The inch is a unit of length in the imperial and US customary systems, defined as exactly 25.4 millimeters.
1 in = 25.4 mm = 2.54 cm = 1/12 ft = 1/36 yd.
To convert inches to cm: multiply by 2.54. To convert cm to inches: divide by 2.54.
Screen sizes (TVs, monitors), drill bit sizes, pipe diameters, screw dimensions, and rainfall measurement in the US.
King Edward II of England defined the inch as 'three grains of barley, dry and round, placed end to end' in 1324.
Forgetting that fractions of an inch use powers of 2 (1/2, 1/4, 1/8, 1/16), not decimal subdivisions like metric.
Your thumb from tip to first knuckle is roughly 1 inch — a handy (literal) reference.
The Earth's equatorial radius is the distance from Earth's center to the equator, approximately 6,378.137 km.
R⊕(eq) = 6,378,137 m = 6,378.137 km. Earth's oblateness = (R_eq − R_pol)/R_eq ≈ 1/298.257.
To convert Earth radii to meters: multiply by 6,378,137.
GPS calculations, satellite orbit determination, map projections, and geophysical modeling.
Earth is not a perfect sphere — the equatorial radius is about 21 km (0.3%) larger than the polar radius due to rotational flattening.
Using the equatorial radius as if Earth were a sphere — for precision, you must account for the oblate spheroid shape.
Earth's equatorial radius (6,378 km) vs. polar radius (6,357 km) shows the planet bulges at the equator due to spinning.



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