Skip to content
Allin
Sign up · Sign in

Arccos Calculator

Find the inverse cosine (arccos) of a value between −1 and 1, in degrees and radians.

Related tools

All Trigonometry tools →
Arcsin CalculatorFind the inverse sine (arcsin) of a value between −1 and 1, in degrees and radians.Arctan CalculatorFind the inverse tangent (arctan) of any real value, in degrees and radians.Cosecant, Secant & Cotangent CalculatorGet csc, sec and cot for any angle at once, with undefined values flagged.Sine CalculatorCompute the sine of any angle in degrees or radians, to your chosen precision.Tangent Line to Circle CalculatorThe tangent lines from a point to a circle, with the tangent length and a live diagram.Trigonometric Equation SolverSolve sin, cos and tan equations on any interval by robust numerical root-finding — results as multiples of π, radians and degrees, with interval presets for [0,2π], [−π,π], [0,4π] and [0°,360°].Trigonometric Function GrapherPlot A·f(Bx − C) + D for sin, cos, tan, cot, sec and csc with the asymptotes drawn, plus amplitude, period, phase shift, midline, domain, range and key points.Trigonometric Identities CalculatorFrom one known function value and a quadrant, rebuild all six functions with the right signs, then check the Pythagorean, reciprocal, double-angle and half-angle identities.

Arccos Calculator works straight from this page — free, instant, nothing to install. Its place is under Trigonometry; Arcsin Calculator and Arctan Calculator answer the questions closest to this one.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Arccos Calculator?

Find the inverse cosine (arccos) of a value between −1 and 1, in degrees and radians.

When would I actually use this?

Solving a triangle from what you can actually measure, converting between degrees and radians, and checking an identity before using it.

What is the most common mistake?

Leaving the calculator in the wrong angle mode. Degrees and radians differ by a factor of about 57, and the answer is wrong without ever looking wrong.

How is Arccos Calculator different from Arcsin Calculator?

They sit next to each other but answer different questions: Arcsin Calculator is the one to open when you need it to find the inverse sine (arcsin) of a value between −1 and 1, in degrees and radians. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Arctan Calculator is the closest one after this: Find the inverse tangent (arctan) of any real value, in degrees and radians.

What else is worth having open alongside it?

Cosecant, Secant & Cotangent Calculator and Sine Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

The identities are the classical ones and the arithmetic is exact to double precision. The law-of-sines case with two sides and a non-included angle can have two valid triangles, and both are reported.

Further reading

All guides →
ExplainerThe Flat Pattern of a Cone Is a Sector, Not a CircleRoll a 50 mm cone 80 mm tall and its pattern is a 190.8° slice of a 94 mm circle. Flatten a nearly cylindrical lampshade and the pattern radius runs to 839 mm — the shallower the taper, the further away the apex.ExplainerA 1 % Drop Rate Does Not Mean One Hundred RunsAt 1 %, a hundred attempts give you 63.4 % — not certainty. Ninety per cent takes 230 attempts and ninety-nine takes 459, and more than a third of players are still empty-handed at a hundred.ExplainerFibonacci and the Golden RatioThe Fibonacci sequence adds each pair of terms to make the next; the ratio of neighboring terms homes in on the golden ratio φ ≈ 1.618. See how, and where the pattern turns up.ExplainerWhat Is a Z-Score? Standard Deviations Above the MeanA z-score is z = (x − μ) / σ — how many standard deviations a value sits from the mean. Learn how to compute it, read the standard normal curve, and turn it into a percentile.How-toHow to Find the Distance Between Two PointsUse the distance formula d = √((x₂−x₁)² + (y₂−y₁)²) to measure the straight-line distance between two points on a plane, with a worked example and the midpoint too.How-toHow to Calculate the Slope of a Line: Rise Over RunFind the slope of a line from two points with m = (y₂ − y₁) / (x₂ − x₁), and read what a positive, negative, zero, or undefined slope tells you.