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Circular Curve Calculator

Enter any two of radius, arc length, long chord, whole central/intersection angle or tangent length to calculate the remaining simple-curve geometry, mid-ordinate, external and circular-segment area. The supported branch is one minor curve with a central angle greater than 0° and less than 180°.

Caltrans BDD 2.4 Attachment 2E · June 2025 · pp 1–2WSDOT Field Formulas M 22-24 · 1998 · pp 5, 17

Uses only this tool title and its public link. Inputs, results, coordinates and filenames are not included. Sharing starts only when you press the button.

Free advisory field tool — every result is computed in your browser from the inputs you provide and is advisory and unverified, not for survey deliverables. Where a published guideline applies, results only ever read “within guideline” or “exceeds guideline — review”. The full working is shown for every calculation so each step can be re-checked. Registered surveyor confirmation required before reliance.

Input pair

Enter any two curve values

Values describe one simple minor curve. Delta is the whole central/intersection angle, not a tangent-to-chord half-angle.

DD or DMS; open range 0 degrees to 180 degrees

Enter calculates from a single-line field. Enter still adds a new line in pasted lists.

Calculated geometry

Curve result

Enter two values to calculate the curve.

Angle convention: delta is the whole central/intersection angle. A tangent-to-chord deflection is a half-angle and must not be entered as delta. Near-degenerate warnings identify the displayed DMS resolution boundary; they are not project tolerances.

Advisory output — confirm independently before reliance.

Method

How to use the horizontal curve calculator

Choose two supported values for one simple minor circular curve and review the solved geometry with its formula trace.

  1. Choose two known values

    Select any two supported principal values: radius, arc length, long chord, whole central angle or tangent length.

  2. Enter the curve data

    Enter positive values and use decimal degrees or DMS for the whole central angle, or load the fictional example.

  3. Review the solved geometry

    Inspect every derived value, any input cue and the full formula trace before carrying the result into other work.

Australian surveying FAQ

Questions about Circular curve calculator

What does a horizontal curve calculator calculate for surveying?

For one simple minor circular curve, it solves the remaining principal geometry plus mid-ordinate, external and circular-segment area from two supported inputs.

Which two circular-curve values can I enter?

Choose any two of radius, arc length, long chord, whole central angle or tangent length. The pair must describe a possible simple minor curve.

Is tangent-to-chord deflection the same as the whole central angle?

No. The page expects the whole central or intersection angle. A tangent-to-chord deflection is a half-angle and must not be entered as delta.

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COGO — bearing, distance & area Vertical curve calculator Radial set-out sheet Docs hub — working-data guides All field tools

Safety & scope

SurveyMarkup helps prepare and review working information. Every professional decision remains with the registered surveyor, and original data and final outputs require qualified review.

Assistance only - professional review remains required.