What is the syntax for RADIANS in Excel?

The syntax for RADIANS is: =RADIANS(angle)

Why do I need RADIANS for trigonometric functions?

Excel's trig functions (SIN, COS, TAN) expect angles in radians, not degrees. RADIANS converts degrees to radians: =SIN(RADIANS(90)) correctly returns 1, while =SIN(90) treats 90 as radians and returns 0.894.

What is the formula RADIANS uses?

RADIANS multiplies degrees by π/180. So =RADIANS(180) = 180 × π/180 = π ≈ 3.14159. You could write =angle*PI()/180 instead, but RADIANS is cleaner and more readable.

How do I convert radians back to degrees?

Use the DEGREES function: =DEGREES(PI()) returns 180. DEGREES multiplies radians by 180/π. These are inverse functions: DEGREES(RADIANS(x)) = x and RADIANS(DEGREES(x)) = x.

Math & Trig

RADIANS Function in Excel

Converts degrees to radians.

Syntax

=RADIANS(angle)

Arguments

angle (required): Angle in degrees to convert

Examples

=RADIANS(180) - 180 degrees in radians - Result: 3.14159...
=RADIANS(90) - 90 degrees in radians - Result: 1.5708...

RADIANS in reporting workflows

Use absolute references when copying formulas across rows.
For conditional totals see [SUMIF](/functions/sumif/) and [SUMIFS](/functions/sumifs/).
Filtered lists may need [SUBTOTAL](/functions/subtotal/) instead of SUM on visible cells only.

Common errors

None common

Use cases

Trig function input
Angle conversions
Scientific calculations

Frequently asked questions

Why do I need RADIANS for trigonometric functions? Excel's trig functions (SIN, COS, TAN) expect angles in radians, not degrees. RADIANS converts degrees to radians: =SIN(RADIANS(90)) correctly returns 1, while =SIN(90) treats 90 as radians and returns 0.894.
What is the formula RADIANS uses? RADIANS multiplies degrees by π/180. So =RADIANS(180) = 180 × π/180 = π ≈ 3.14159. You could write =angle*PI()/180 instead, but RADIANS is cleaner and more readable.
How do I convert radians back to degrees? Use the DEGREES function: =DEGREES(PI()) returns 180. DEGREES multiplies radians by 180/π. These are inverse functions: DEGREES(RADIANS(x)) = x and RADIANS(DEGREES(x)) = x.

Editorial review

Reviewed by Excel.Directory Editorial Team. Updated May 2026.