COS Function in Excel: Cosine of an Angle

⏱ 1 min readUpdated 28 September 2026

MathLevel: IntermediateAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. Related functions

COS also expects radians. Seasonal models sometimes use SIN and COS of the month to capture yearly cycles.

Syntax

=COS(number)
Argument What it means
number Angle in radians.

Examples

Example 1

=COS(2*PI()*MONTH(A2)/12)

A smooth yearly-cycle feature for a forecast model.

SIN · PI

📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.

✨ Ask AI about this article

Stuck on a step? Ask a question and the AI answers using this article.

Free · AI can be wrong