Circular Inch to Square Foot (US Survey) Converter
Unit Converter
Instant · Precise · Universal
23 units available
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How to Convert Circular Inch to Square Foot (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) = 0.005454132095 Square Foot (US Survey) (ft² (US)).
Circular Inch to Square Foot (US Survey) — Common Values
| Circular Inch (circ in) | Square Foot (US Survey) (ft² (US)) |
|---|---|
| 0.1 | 0.0005454132095 |
| 0.5 | 0.002727066047 |
| 1 | 0.005454132095 |
| 2 | 0.01090826419 |
| 5 | 0.02727066047 |
| 10 | 0.05454132095 |
| 25 | 0.1363533024 |
| 50 | 0.2727066047 |
| 100 | 0.5454132095 |
| 500 | 2.727066047 |
| 1000 | 5.454132095 |
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 Foot (US Survey) (ft² (US))
Definition
The US survey square foot is a historical area unit based on the US survey foot (1200/3937 m), equal to approximately 0.09290341 m².
Mathematical Relationship
1 ft² (US) ≈ 0.09290341 m². Differs from international ft² (0.09290304 m²) by about 4 × 10⁻⁷ m².
Conversion Formula
To convert US survey ft² to m²: multiply by 0.09290341. To international ft²: multiply by ~1.000004.
Practical Applications
Historical property records and government land survey documents.
Interesting Facts
The difference from the international square foot is only about 0.4 mm² — negligible for a single measurement, but significant over millions of square feet.
Common Mistakes
Using the US survey foot in new work. Since 2023, only the international foot is valid in the US.
Educational Tips
The US survey foot existed because of a historical definition difference. It's now retired — use the international foot (exactly 0.3048 m).