Circular Inch to Square Mile (US Survey) Converter
Unit Converter
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23 units available
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How to Convert Circular Inch to Square Mile (US Survey)
To convert circular inches to in²: multiply by 0.7854. To cm²: multiply by 5.067.
1 circular inch = π/4 in² ≈ 0.7854 in² ≈ 5.067 cm². Equals 1,000,000 circular mils.
For example, 1 Circular Inch (circ in) = 1.956401e-10 Square Mile (US Survey) (mi² (US)).
Circular Inch to Square Mile (US Survey) — Common Values
| Circular Inch (circ in) | Square Mile (US Survey) (mi² (US)) |
|---|---|
| 0.1 | 1.956401e-11 |
| 0.5 | 9.782003e-11 |
| 1 | 1.956401e-10 |
| 2 | 3.912801e-10 |
| 5 | 9.782003e-10 |
| 10 | 1.956401e-9 |
| 25 | 4.891002e-9 |
| 50 | 9.782003e-9 |
| 100 | 1.956401e-8 |
| 500 | 9.782003e-8 |
| 1000 | 1.956401e-7 |
About Circular Inch (circ in)
Definition
The circular inch is the area of a circle one inch in diameter, equal to π/4 square inches (approximately 0.0005067 m²).
Mathematical Relationship
1 circular inch = π/4 in² ≈ 0.7854 in² ≈ 5.067 cm². Equals 1,000,000 circular mils.
Conversion Formula
To convert circular inches to in²: multiply by 0.7854. To cm²: multiply by 5.067.
Practical Applications
Wire and cable cross-section calculations, especially for large conductors in power distribution.
Interesting Facts
The circular mil and circular inch exist solely to avoid π in cross-section math. Diameter² (in circular units) directly gives the area.
Common Mistakes
Confusing circular inch with square inch — a circular inch is about 78.5% of a square inch.
Educational Tips
For a circle: area in circular inches = diameter². Area in square inches = diameter² × π/4. The circular unit absorbs the π/4 factor.
About Square Mile (US Survey) (mi² (US))
Definition
The US survey square mile is a historical area unit based on the US survey foot, equal to approximately 2,589,998.47 m².
Mathematical Relationship
1 mi² (US) ≈ 2,589,998.47 m². Differs from international mi² (2,589,988.11 m²) by about 10.36 m².
Conversion Formula
To convert US survey mi² to km²: multiply by 2.590. To international mi²: multiply by ~1.000004.
Practical Applications
Historical US Public Land Survey System sections (each nominally 1 mi² US survey).
Interesting Facts
Over one square mile, the US survey definition differs from the international definition by about 10.4 m² — roughly a 3 m × 3.5 m room.
Common Mistakes
Using the US survey mile for new calculations. Deprecated since 2023 — use the international definitions.
Educational Tips
The US Survey system was a legacy from 1893. Its 2023 retirement unified US measurements with the international standard.