Small-angle distance estimate calculator

Calculate small-angle distance and exact tangent-plane distance with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use small-angle distance and exact tangent-plane distance to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Physical size (chosen length unit)
10
Angular size (arcseconds)
30
Small-angle distance (same length unit)
68,754.935416
Exact tangent-plane distance (same unit)
68,754.935294
Relative approximation difference (%)
0

Try another scenario

Physical size (chosen length unit)
11
Angular size (arcseconds)
30
Small-angle distance (same length unit)
75,630.428957
Exact tangent-plane distance (same unit)
75,630.428824
Relative approximation difference (%)
0
Calculation method

Calculation method

Small-angle distance (same length unit)

Small-angle distance=linearSize/angle; exact planar full-width geometry distance=linearSize/(2tan(angle/2)).

Exact tangent-plane distance (same unit)

Small-angle distance=linearSize/angle; exact planar full-width geometry distance=linearSize/(2tan(angle/2)).

Relative approximation difference (%)

Small-angle distance=linearSize/angle; exact planar full-width geometry distance=linearSize/(2tan(angle/2)).

Symbols and units
a
Physical size (chosen length unit)
b
Angular size (arcseconds)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • Small-angle approximation, maximum angle one degree. Supported limits: All required fields must be finite values of the exact declared type and within displayed bounds. Lists contain1–1000 finite numbers. JSON tables are numeric rectangular rows, at most100 rows and30 columns; individual tools have stricter shape/domain constraints. Small-angle approximation, maximum angle one degree.
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