Inverse Tangent Calculator arctan(x)

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Below is an inverse tangent calculator (or arctan calculator), which calculates an angle from the ratio from the tangent function. Enter a result and choose to return radians or degrees, then compute the angle.

Inverse Tangent Calculator

Using the Arctangent Calculator

To use the tool to find the angle from a tangent, enter the ratio and the units you'd like and compute.

  • Tangent - ratio of the opposite side to the adjacent side
  • Output Degrees or Radians? - choose to return degrees or radians

Once you're happy, click the "Compute Arctan" button.

  • Angle - the angle you'd input if you wanted to get the tangent you entered

What is the arctangent or inverse tangent?

Arctangent is the inverse of the tangent, which is the ratio of the opposite side to the adjacent side in a right triangle.

Right triangle to illustrate trigonometry functions
Right Triangle Diagram (CC By-SA 3.0 Wikimedia)

Arctangent as a formula

Inverse tangent is usually abbreviated as "arctan" or "atan", as in the following equation:


Where it is the inverse of tangent, or:


Next, see all the inverse trigonometric functions or trigonometric functions in one tool.



PK started DQYDJ in 2009 to research and discuss finance and investing and help answer financial questions. He's expanded DQYDJ to build visualizations, calculators, and interactive tools.

PK lives in New Hampshire with his wife, kids, and dog.

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