This railroad curve calculator converts between the degree of curve and the radius for horizontal railway and highway curves. Enter either value above to get the other.
Formula (arc definition)
Degree of curve D = 5729.58 ÷ R Radius R = 5729.58 ÷ D
The degree of curve is the central angle over a 100-foot arc.
Example
D = 2°: R = 5729.58 ÷ 2 = 2864.8 ft.
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Frequently Asked Questions
How do I calculate degree of curve?
Divide 5729.58 by the radius in feet. A 2864.8 ft radius gives a 2-degree curve by the arc definition.
What is the degree of curve?
It is the central angle subtended by a 100-foot arc of the curve; a sharper curve has a higher degree.
What is the difference between arc and chord definition?
The arc definition uses a 100-ft arc (common for railways); the chord definition uses a 100-ft chord (common for roads).