The inverse tangent function — given a ratio, this finds the angle whose tangent equals that ratio.
How it works
The arctangent of the entered value is computed and shown in both degrees and radians.
What this does not include
This does not include the two-argument atan2 form used for coordinate conversion — for that, use this site’s rectangular to polar calculator instead.
How to use this calculator
- Enter the value you want the arctangent of.
Frequently asked questions
Why does tan⁻¹(1) equal 45°?
Because the tangent of 45° is exactly 1 — the arctangent function simply reverses that relationship.
What’s the range of possible outputs?
Arctangent always returns an angle between -90° and 90°, since tangent repeats every 180°.
Is this the same as 1/tan(x)?
No — tan⁻¹(x) means “the angle whose tangent is x,” while 1/tan(x) is the reciprocal of the tangent function (cotangent), a different operation entirely.
