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TAN Function

Excel 2007+

Summary

The Excel TAN function calculates the tangent of a specified angle provided in radians. This trigonometric function is essential for mathematical computations, engineering calculations, and geometric analysis within spreadsheets.

Syntax

TAN(number)

Parameters

Parameter	Type	Required	Description
number	`Number`	Yes	The angle value in radians. Must be a numeric value.

Using the TAN Function

TAN is a fundamental trigonometric function used when you need the tangent ratio of an angle. Input the angle in radians directly, or convert degrees using PI()/180 multiplication or the RADIANS function for degree-based calculations.

Common TAN Examples

Tangent of Radian Value

=TAN(0.785)

Calculates tangent of approximately 45 degrees in radians, returns ~0.99920

Convert Degrees to Radians with PI()

=TAN(45*PI()/180)

Tangent of exactly 45 degrees, returns 1

Using RADIANS Function

=TAN(RADIANS(45))

Alternative method to convert 45 degrees to radians and get tangent value of 1

Frequently Asked Questions

TAN requires input in radians. Convert degrees using RADIANS(degrees) or degrees*PI()/180.

TAN returns #VALUE! error for text or invalid inputs.

Common Errors and Solutions

#VALUE!

Cause: Non-numeric argument provided

Solution: Ensure input is a valid number

#NUM!

Cause: Calculation results in domain error

Solution: Verify angle value is appropriate

Notes

Tangent equals opposite over adjacent in right triangles
Periodic every π radians
Convert degrees: multiply by PI()/180
Use with SIN and COS for comprehensive trig analysis

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in:

Content last reviewed: December 11, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+