geoprimsField-grade geospatial math

Angle converter

Converts angles: degrees, radians, gons, arcminutes, arcseconds, turns, and the four kinds of mil.

90°

1,600 NATO mils is 90°.

Input
Provenance
Computed by
units.angle.convert 1.0.0, core 0.1.0
Model
Exact unit definitions
Accuracy
Exact to double precision: each conversion is one correctly rounded ratio of exact definitions
Notes
None
Cites
National Institute of Standards and Technology, Guide for the Use of the International System of Units (SI), NIST Special Publication 811

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How we got thisFormula, worked example, sources, and proof

Model: Exact unit definitions

Accuracy: Exact to double precision: each conversion is one correctly rounded ratio of exact definitions

When to use this: Use this wherever an angle crosses between trades: a bearing in degrees against a calculation in radians, a survey angle in gons, a sight in mils, a catalogue position in milliarcseconds, a slope in milliradians. The three military mils are all here and kept apart, which is the point — they divide the circle 6,400, 6,000 and 6,300 ways, so the same number of mils is a different angle depending on whose manual it came from.

Limitations: This converts the size of an angle and knows nothing about what it points at: it will not wrap a bearing into 0-360, decide whether an angle is measured from north or from east, or tell a heading from a course. Those are the coordinate and bearing tools. Radians and milliradians involve pi, which is not a ratio of whole numbers, so those conversions carry a slightly looser tolerance than the rest -- still far below any angle anyone measures. A mil given without saying which mil is the one error this tool cannot catch for you.

Worked example: 1,600 NATO mils in degrees. Source: Exact unit definitions (NIST SP 811 Appendix B). It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.

You enter

To unit
deg
Value
1600 mil-nato

You get

Converted
90°
Input
1,600 NATO mils

Review: Not yet independently reviewed by a metrologist.

Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Checked against: 110 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources