Trigonometry Calculator

sin, cos, tan and the whole gang — type an angle and get every ratio without cracking a textbook.

What this calculator does

Enter an angle and this tool returns its six trigonometric ratios: sine, cosine, and tangent, plus their reciprocals cosecant, secant, and cotangent. It also runs the inverse functions, so if you already have a ratio, you can work backward to the angle that produced it. You choose whether your angle is measured in degrees or radians, which matters more than most people expect: sin(90) is 1 in degrees but roughly 0.894 in radians.

When you'd actually use it

Trig ratios show up any time a right triangle is hiding inside a problem. Students checking homework use it to confirm SOH-CAH-TOA answers. Woodworkers and DIYers use tangent to figure out a rafter angle or a ramp's rise over run. Someone laying out a garden bed uses cosine to find a diagonal. Physics and engineering problems lean on it for resolving forces and vectors into horizontal and vertical components. The inverse functions are handy in reverse: you measured the two legs of a triangle and need the angle between them, so you feed the ratio into arctangent.

A quick worked example

Say a ladder leans against a wall at 75°. To find how far its base sits from the wall relative to its length, take cos(75°) ≈ 0.259 — so the base is about a quarter of the ladder's length out from the wall. Need the angle instead? If the base is 3 ft out and the ladder is 12 ft long, cos of the angle is 3 ÷ 12 = 0.25, and arccos(0.25) ≈ 75.5°.

How to use it

Pick your unit — degrees or radians — before typing anything, since it changes every result.
Type your angle into the input field (for inverse functions, enter the ratio value instead).
Read off sine, cosine, tangent, and the three reciprocals, or the inverse result if you're solving for an angle.
Change the angle and the values update instantly — no button-mashing needed to compare a few angles.

FAQ

Why does tangent sometimes show an error or "undefined"?: Tangent is sine divided by cosine, and cosine is zero at 90°, 270°, and so on. Dividing by zero has no value, so tangent is genuinely undefined there rather than a huge number.
How do I convert between degrees and radians myself?: Multiply degrees by π/180 to get radians, or multiply radians by 180/π to get degrees. A full circle is 360° or 2π radians.
Is anything sent to a server?: No. The math runs entirely in your browser, so nothing you type ever leaves your device.
Is it free?: Yes, it's free and supported by the ads on the page.