Cosh Calculator - Hyperbolic Cosine Function

Use this free cosh calculator to evaluate the hyperbolic cosine of any real number, with sinh, tanh, and an inline identity check to confirm the result.

Updated: June 16, 2026 • Free Tool

Cosh Calculator

Cosh accepts any real x. Values with |x| greater than about 709 overflow IEEE 754 doubles and return an overflow warning.

Results

cosh(x)
0
sinh(x) 0
tanh(x) 0
Identity check: cosh^2 - sinh^2 0

What Is a Cosh Calculator?

A cosh calculator evaluates the hyperbolic cosine of any real number using the exponential definition cosh(x) = (e^x + e^-x) / 2. The hyperbolic cosine shows up in physics, engineering, and statistics whenever a problem involves a catenary cable, the Lorentz factor from special relativity, or a probability density that uses the hyperbolic secant. This cosh calculator returns cosh, sinh, and tanh in a single pass, then runs the cosh^2 - sinh^2 = 1 identity check on the same numbers so you can see the identity hold in real time.

  • Solving catenary cable problems: Compute cosh(x / a) terms that appear in the catenary equation y = a cosh(x / a) for hanging cables, suspension chains, and transmission lines.
  • Working with the Lorentz factor: Evaluate cosh of a rapidity value when reading or writing the hyperbolic form of the Lorentz factor gamma = cosh(rapidity) in special relativity.
  • Verifying hyperbolic identities in homework: Confirm identities such as cosh^2(x) - sinh^2(x) = 1 or 1 - tanh^2(x) = sech^2(x) while working through calculus or differential equations problems.
  • Generating reference values for code: Look up cosh, sinh, and tanh for a list of x values to paste into a spreadsheet, a numerical script, or a finite-element model that needs hyperbolic inputs.

Cosh is one of three core hyperbolic functions, alongside sinh and tanh. The three are defined together because they share the same exponential family and the same set of identities. Cosh behaves a little like ordinary cosine: it is smooth, even, and unbounded above. It differs in two important ways: cosh(x) is always at least 1, so its range is [1, infinity) instead of [-1, 1], and cosh and sinh combine into the identity cosh^2 - sinh^2 = 1, where the sign is negative.

Because cosh is built from e^x and e^-x, the Exponential Notation Calculator is a useful companion when you want to look up the underlying exponential values that drive the result.

How the Cosh Calculator Works

The calculator reads x from the input field, runs the exponential definition of cosh, and reports the result alongside the matching sinh, tanh, and an inline identity check. Every value is computed in IEEE 754 double-precision arithmetic, and the identity check is recomputed from the same cosh and sinh so any rounding error is visible at the bottom of the results panel.

cosh(x) = (e^x + e^-x) / 2
  • x: The real number you enter. Cosh accepts any real x, including negatives, zero, and large positives up to about 709 before the exponential overflows.
  • e: Euler's number, approximately 2.7182818284590452. It is the base of the natural exponential that defines the whole hyperbolic family.
  • cosh(x): The hyperbolic cosine of x, equal to the average of e^x and e^-x. Always greater than or equal to 1 for real x.

The same calculation chain also returns sinh and tanh for the same x. Sinh uses the difference of the two exponentials divided by 2, and tanh is the ratio of sinh to cosh. Showing all three together makes the identity check at the bottom of the results panel read like a self-test rather than a black-box answer.

Worked example: cosh(1)

x = 1, with the result read to six significant digits

Compute e^1 ≈ 2.7182818 and e^-1 ≈ 0.3678794, then average them: cosh(1) = (2.7182818 + 0.3678794) / 2 ≈ 1.5430806.

cosh(1) ≈ 1.5430806, with sinh(1) ≈ 1.1752012 and tanh(1) ≈ 0.7615942

Cosh of 1 sits between 1 and e, because the average of e and 1/e pulls the result toward the geometric mean of the two exponentials.

According to Wikipedia: Hyperbolic functions, the hyperbolic cosine is defined as cosh(x) = (e^x + e^-x) / 2 and satisfies the identity cosh^2(x) - sinh^2(x) = 1 for every real x

If you came here from a trigonometry problem, the Arccos Calculator is the closest neighbour on the principal-branch side and shares the same function-style framing.

Key Concepts Behind Cosh

These four concepts explain what the result means, why cosh is even, and why the identity check is a useful sanity test for the numbers you just computed.

Exponential definition

Cosh is defined by exponentials: cosh(x) = (e^x + e^-x) / 2. The same definition is the source of every identity and limit, and it is the form the calculator uses internally to avoid relying on a built-in cosh routine.

Even function

Cosh is an even function, so cosh(-x) = cosh(x) for every real x. Swap the sign of x and the result stays the same, which is why the calculator shows the same cosh value for x = 2 and x = -2.

Range [1, infinity)

Cosh is always greater than or equal to 1 for real inputs and is unbounded above. The minimum 1 occurs at x = 0, and the function grows roughly like e^x / 2 once x is larger than about 3.

Pythagorean-style identity

Cosh and sinh combine into cosh^2(x) - sinh^2(x) = 1, the hyperbolic analogue of the ordinary Pythagorean identity. The sign is negative because cosh and sinh come from exponentials, not from a unit circle.

The four concepts are linked: the exponential definition produces the even function, the even function forces the range to start at 1, and the Pythagorean-style identity falls out of the same exponential algebra. The minus sign in cosh^2 - sinh^2 = 1 is the only place a subtraction shows up in the trig family, because the underlying definition uses a sum and a difference of exponentials rather than a sum of squares.

The principal-branch framing that the Arcsin Calculator uses for inverse sine applies equally well to the even-function behaviour of cosh.

How to Use This Cosh Calculator

Working with the calculator only takes a few seconds: enter x, read the three hyperbolic results, and check the identity row to confirm the numbers agree with the cosh^2 - sinh^2 = 1 identity.

  1. 1 Enter x: Type a real number in the input box. Use 0, 1, 2, 10, or a negative value to test the typical use cases the page calls out.
  2. 2 Read cosh, sinh, and tanh: The big result tile shows cosh(x) and the rows below show sinh(x) and tanh(x). All three update live as you type or change x.
  3. 3 Check the identity row: Look at the bottom row labelled 'Identity check: cosh^2 - sinh^2'. It should sit at 1 to within floating-point precision when the inputs are well-behaved.
  4. 4 Try a negative or large positive x: Enter a negative number such as -2 to confirm cosh is even, or a large value such as 10 to watch cosh and sinh grow toward the same magnitude while tanh approaches 1.
  5. 5 Watch for overflow warnings: If |x| passes about 709, the exponential overflows IEEE 754 doubles and the calculator returns a clear overflow message instead of producing Infinity.

For a 200-metre chain with parameter a = 50 metres, evaluated at x = 75 metres, the height is y = 50 cosh(75 / 50) = 50 cosh(1.5). Enter 1.5, read cosh ≈ 2.3524096, multiply by 50 in your workbook, and confirm the identity check at the bottom of the results panel reads 1. The cosh calculator turns the chain's x value into the height offset without manual exponential arithmetic.

When the chain angle at the support point matters, the slope is tanh(x / a) and the Arctan Calculator handles the inverse-tangent step in the same math-conversion family.

Benefits of This Cosh Calculator

A cosh calculator that shows cosh, sinh, tanh, and an identity check in one panel saves a lot of table-lookup time and removes the most common arithmetic mistakes.

  • Three hyperbolic results in one pass: Get cosh(x), sinh(x), and tanh(x) for the same x without re-entering the input or recomputing exponentials in a separate tool.
  • Built-in identity check: The bottom row recomputes cosh^2 - sinh^2 from the same numbers, so a typo in the input or a sign error in a derivation shows up as a residual that is not 1.
  • Even-function validation: Type x = 2 and x = -2 to confirm cosh is even. The two cosh values match, while sinh flips sign, which is the textbook behaviour of the hyperbolic family.
  • Overflow-aware for large x: The calculator flags inputs with |x| greater than about 709 with a clear message, so IEEE 754 overflow does not silently return Infinity inside a larger calculation.
  • Reference values for tables and code: Read off cosh, sinh, and tanh for a list of x values in seconds and paste them straight into a spreadsheet, a finite-element script, or a probability model.

The biggest practical win is the identity check. Recomputing cosh^2 - sinh^2 from the displayed values is the quickest way to spot a sign error in handwritten work, because any deviation from 1 points to a mistake in the original calculation rather than in the tool.

If the cosh result feeds into an arc length such as the catenary arc s = a sinh(x / a), the Arc Length Calculator handles the surrounding geometry in the same math-conversion category.

Factors That Affect Your Cosh Result

A handful of factors control what the calculator can return. Knowing them up front prevents the most common mistakes, especially when x is near the overflow boundary.

Sign of x

Cosh is even, so cosh(x) = cosh(-x). Negative inputs do not change the cosh result but they do flip the sign of sinh, which is why the calculator shows sinh(-2) = -sinh(2).

Magnitude of x

For |x| greater than about 3, cosh is dominated by e^x / 2 and the result grows very quickly. Past x = 10 the numbers are large enough to need scientific-notation display in any downstream work.

Floating-point precision

Cosh is computed in IEEE 754 doubles, so the result is exact to about 15 significant digits. Treat the identity check as a sanity check, not an equality test, because tiny residuals are normal at the edge of double precision.

Overflow boundary at |x| near 709

Once |x| is roughly 709, e^x or e^-x exceeds the largest finite double and the calculation overflows. The calculator surfaces this with a clear overflow message rather than returning Infinity.

  • The calculator returns cosh for real x only. It does not compute the complex-valued cosh of a non-real z = a + bi, which would require evaluating e^z and e^-z as complex exponentials.
  • The result is rounded to six significant digits in the display. For higher precision, copy the JavaScript formula in the page source and evaluate it in a tool that supports arbitrary-precision arithmetic.

Beyond the limits above, the only thing that materially changes the result is the input itself. Cosh has no parameters, no modes, and no unit settings, so once x is in the input box the four rows in the results panel are fully determined.

According to Wolfram MathWorld: Hyperbolic Cosine, cosh(x) is an even function, reaches its minimum value of 1 at x = 0, and grows like e^x / 2 for large positive x

According to Paul's Online Math Notes: Hyperbolic Functions, the hyperbolic functions are defined by exponentials and obey identities such as cosh^2(x) - sinh^2(x) = 1 and 1 - tanh^2(x) = sech^2(x)

Cosh calculator input panel showing a real x value and matching cosh, sinh, tanh, and identity check result fields
Cosh calculator input panel showing a real x value and matching cosh, sinh, tanh, and identity check result fields

Frequently Asked Questions

Q: What is cosh?

A: Cosh is the hyperbolic cosine, a function defined by cosh(x) = (e^x + e^-x) / 2. It behaves a little like ordinary cosine but uses exponentials instead of angles, and it is even, smooth, and always greater than or equal to 1 for any real input.

Q: How do you calculate cosh by hand?

A: Compute e^x and e^-x with a calculator, add the two values, and divide the result by 2. For x = 0, both exponentials equal 1, so cosh(0) = (1 + 1) / 2 = 1. For x = 1, e^1 ≈ 2.7183 and e^-1 ≈ 0.3679, giving cosh(1) ≈ 1.5431.

Q: What is the range of cosh?

A: Cosh of a real number always returns a value greater than or equal to 1. The minimum 1 occurs at x = 0, and cosh grows roughly like e^x / 2 for large positive x. There is no real input that makes cosh less than 1.

Q: Is cosh the same as cosine?

A: No. Cosine of an angle uses a unit circle and returns values in the closed interval [-1, 1], while cosh uses exponentials and returns values in [1, infinity). They share the identity cos^2 + sin^2 = 1 with the analogous cosh^2 - sinh^2 = 1, but the sign in the middle is different.

Q: What is cosh of 0?

A: Cosh of 0 is exactly 1, because (e^0 + e^0) / 2 = (1 + 1) / 2 = 1. The cosh calculator returns 1 for x = 0 along with sinh(0) = 0 and tanh(0) = 0, which all satisfy the hyperbolic identity check.

Q: Why does cosh only produce values greater than or equal to 1?

A: Cosh is the average of e^x and e^-x, and the arithmetic mean of two positive numbers is always at least the smaller of the two. The two exponentials meet at 1 when x = 0 and pull apart as |x| grows, so cosh(0) = 1 is the absolute minimum on the real line.