Radians to Gradians Calculator

Direct answer

Multiply the entered radians value by 63.6619772367778 to express it in gradians (gon). This converts radian (rad) to gradian (gon) within the documented angle family.

Variables and formula

• Radians (rad): the source value measured in radian.
• Gradians (gon): the same quantity expressed in gradian.
• Conversion factor: 63.6619772367778 gradians per radian.

Gradians = Radians × 63.6619772367778

The generator emits numeric factors with at most 15 significant digits. Calculator results keep up to 10 significant digits for display; this formatting does not increase the precision of the measurement.

Unit definitions and named variants

Source unit: radian (rad). The radian is the coherent SI unit for plane angle. One radian is the angle subtended by an arc equal in length to the radius; equivalently, a right angle is π/2 rad and 1 rad = 180/π degrees. Named variant used: Coherent SI unit of plane angle; rad can also name the obsolete absorbed-dose unit in unrelated contexts. Reference: Bureau International des Poids et Mesures: The International System of Units (SI), 9th edition, version 4.01.

Target unit: gradian (gon). A gradian (gon) divides a full turn into 400 parts, so 1 gon = 0.9° exactly. Named variant used: Plane-angle gradian/gon; not a percentage grade or academic grade. Reference: National Institute of Standards and Technology: NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically.

The rad-to-gon direction remains inside the angle quantity; it changes the unit label and numerical scale, not the kind of quantity being measured.

Relationship and precision

This route uses at least one deliberately preserved rounded factor. Treat the displayed factor as an approximation at the precision documented below.

• rad relationship: The exact degree factor is 180/π ≈ 57.29577951308232. The preserved baseFactor 57.2957795131 is rounded and is about 1.77×10⁻¹¹ degree higher per radian.
• gon relationship: The terminating degree relationship is exact.

To audit the factor through the family base unit, divide the raw dataset factors 57.2957795131 by 0.9. The generator emits that quotient once at 15 significant digits as the canonical direct factor 63.6619772367778; runtime calculations do not divide the already-emitted base factors again.

Reproducible example

For 10 radians, 10 × 63.6619772367778 = 636.619772367778 gradians. Repeating the same multiplication with the stated factor reproduces the displayed conversion before interface rounding.

Directional scale check

Because one radian contains 63.6619772367778 gradians, the target number is larger than the source number for every positive input. Zero maps to zero, while negative inputs are preserved as signed values under the stated direction convention.

Interpretation

Read the result as gradians, not radians. A value entered as rad leaves the calculator labelled gon; this directional distinction matters even when the two units describe the same angle quantity.

Assumptions and limitations

• Negative radians are supported and represent the opposite rotational direction under the user’s convention.
• This family performs linear unit conversion only; it does not normalize angles to [0, 360), (−180, 180], or another interval.
• Radian and degree are explicitly distinct: one right angle is π/2 rad and 90°, so 1 rad = 180/π degrees and 1° = π/180 rad.

Common mistakes

• The angle unit radian is distinct from the obsolete radiation absorbed-dose unit named rad.
• A right angle is 100 gon, not 90 gon.

Continue within the Angle family

See the Angle conversion hub for its five-unit reference table and all 20 directed routes.

• Reverse the direction: Gradians to Radians
• Compare another angle route: Radians to Degrees
• Compare another angle route: Radians to Turns
• Compare another angle route: Radians to Arcminutes
• Compare another angle route: Gradians to Degrees

Assumptions

• The entered value uses radians exactly as labelled.
• Negative radians are supported and represent the opposite rotational direction under the user's convention.
• Rounding and measurement uncertainty remain the user's responsibility.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• The International System of Units (SI), 9th edition, version 4.01; Bureau International des Poids et Mesures; accessed Aug 7, 2026
• NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically; National Institute of Standards and Technology; accessed Aug 7, 2026