ArcTan Calculator
Find the angle whose tangent equals a given value, with principal value in degrees or radians.
About ArcTan Calculator
The inverse tangent (arctan) returns the angle whose tangent equals x. The principal value is in (−90°, 90°) or (−π/2, π/2). Unlike arcsin/arccos, the domain is all real numbers.
Formula
Inverse tangent
θ = arctan(x), for any real x
- x
- The tangent value
- θ
- The resulting angle in (−90°, 90°)
Worked example
With the default values below, ArcTan Calculator returns arctan(x) of 45.00000000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Value (x)
- 1
- Angle unitone of Degrees, Radians
- Degrees
Results
- arctan(x)
- 45.00000000
- Result (degrees)
- 45.000000 °
- Result (radians)
- 0.78539816
Step by step
- 1Input value= 1
- 2Compute arctan= 45° = 0.78539816 rad
- 3Principal range= (−90°, 90°)
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 8 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
What is arctan(1)?
arctan(1) = 45°, because tan(45°) = 1.
Does arctan have a restricted domain?
No. Unlike arcsin and arccos, arctan accepts any real number — the output is always between −90° and 90° (exclusive).