Cosine calculator
Enter an angle and get its cosine straight away. For special angles, such as 30°, 45° and 60°, you also see the exact value, for example cos(60°) = 1/2.
In degrees or radians (choose above). pi/3 works too.
Fill in the fields; the answer appears here straight away.
How it's worked out
How it works
-
Enter the values
Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.
-
Instant answer
The answer appears as you type, with the most important intermediate values.
-
See the working
Under "How it's worked out" you see the steps, handy for checking your own calculation.
What is the cosine?
In a right-angled triangle, the cosine of an angle is the adjacent side divided by the hypotenuse. On the unit circle it is the x-coordinate of the point at that angle, which is why the cosine is always between −1 and 1.
Degrees or radians?
A full turn is 360° or 2π radians, so 60° = π/3 rad. Enter the angle in degrees or radians (choose above). Expressions such as pi/3 or 2pi/5 work too. The result is the same either way; only the unit of the angle differs.
Useful values
cos(0°) = 1, cos(60°) = 1/2, cos(90°) = 0 and cos(180°) = −1. To find the angle that belongs to a cosine, use the arccos calculator. For sine, cosine and tangent together, use the trigonometry calculator.
Frequently asked questions
Is the cosine calculator free?
Yes. The cosine calculator is completely free, with no account, sign-up or usage limit.
How accurate is the result?
The tool calculates with your browser's number precision. For important calculations, always double-check what you entered.
Does it work on my phone?
Yes. The tool works in any modern browser on a phone, tablet or computer.