Circular Inch to Acre (US Survey) Converter
Unit Converter
Instant · Precise · Universal
23 units available
6 categories total
How to Convert Circular Inch to Acre (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) = 1.252096e-7 Acre (US Survey) (ac (US)).
Circular Inch to Acre (US Survey) — Common Values
| Circular Inch (circ in) | Acre (US Survey) (ac (US)) |
|---|---|
| 0.1 | 1.252096e-8 |
| 0.5 | 6.260482e-8 |
| 1 | 1.252096e-7 |
| 2 | 2.504193e-7 |
| 5 | 6.260482e-7 |
| 10 | 0.000001252096441 |
| 25 | 0.000003130241101 |
| 50 | 0.000006260482203 |
| 100 | 0.00001252096441 |
| 500 | 0.00006260482203 |
| 1000 | 0.0001252096441 |
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 Acre (US Survey) (ac (US))
Definition
The US survey acre is a historical unit of area based on the US survey foot, equal to approximately 4,046.873 m².
Mathematical Relationship
1 US survey acre ≈ 4,046.873 m². Differs from international acre (4,046.856 m²) by about 0.016 m².
Conversion Formula
To convert US survey acres to m²: multiply by 4,046.873. To international acres: multiply by ~1.000004.
Practical Applications
Historical US land surveys, old property deeds, and State Plane Coordinate System calculations.
Interesting Facts
The difference between US survey and international acre is about 0.016 m² — roughly the area of a sheet of paper. Over large areas, it adds up.
Common Mistakes
Using US survey acre in new calculations — it's been deprecated since 2023. Use the international acre instead.
Educational Tips
As of 2023, the US survey foot and acre are retired. All US measurements now use the international definitions.