Integral Calculator
Calculate definite integrals of polynomial, trigonometric, and exponential functions over any interval.
About this calculator
This calculator finds the exact definite integral of a chosen function family — polynomial, trigonometric, or exponential — between a Lower and Upper Bound, using the known antiderivative formula for each family rather than a numerical approximation. The Upper Bound has by far the biggest pull on the result of the four movable numeric inputs, well ahead of the Coefficient and the Exponent/Parameter — though Function Type itself moves the result more than any single numeric input does, since switching between polynomial, trig, and exponential swaps the entire antiderivative formula, not just adjusting a coefficient inside a fixed one. That also means the Exponent's direction of pull is not fixed across function types: at the polynomial defaults raising the Exponent lowers the integral (explained below), but for the trig function the same nudge can raise it instead, since sine and its antiderivative flip sign as the frequency parameter sweeps past different multiples of the bounds — a fact about which formula is active, not about the Exponent on its own.
At the calculator's polynomial defaults, the Upper Bound defaults to exactly 1, and 1 raised to any power still returns 1 — so Upper Bound raised to (Exponent plus 1) collapses to exactly 1 and the integral reduces to Coefficient divided by (Exponent plus 1) at these particular settings, meaning the Exponent's own influence here is really just about shrinking or growing that one denominator, not about a changing upper limit of integration the way it would at any other bound. That's also why raising the Exponent at these defaults actually lowers the result rather than raising it: a bigger exponent means dividing the same numerator by a bigger number. The Absolute Area output differs from the signed Definite Integral whenever part of the curve dips below the x-axis across the interval — the definite integral lets those negative and positive regions cancel out, while Absolute Area sums the magnitude of every region regardless of sign, computed separately via a numerical Simpson's-rule pass over the absolute value of the function.
Inputs
Results
Definite Integral
0.33333
How to Use This Calculator
- Select the Function Type (polynomial, trig, exponential) and enter the coefficient and exponent parameters.
- Enter the lower bound (a) and upper bound (b) for a definite integral; the result is the signed area between f(x) and the x-axis.
- Polynomial integrals are computed exactly using the power rule: ∫xⁿ dx = xⁿ⁺¹/(n+1).
- Trigonometric and exponential integrals are computed analytically using standard antiderivative formulas.
- A positive result means more area is above the x-axis in [a,b]; a negative result means more area is below.
- The shaded chart shows the region of integration so you can verify bounds and visualize the area.
How the result changes with Upper Bound (b)
| Upper Bound (b) | Definite Integral |
|---|---|
| 0.5 | 0.04167 |
| 0.75 | 0.14063 |
| 1.5 | 1.125 |
| 2.5 | 5.20833 |
What each input means
- Function Type
- Type of function to integrate
- Coefficient (c)
- Leading coefficient
- Parameter (n)
- Exponent for polynomial, frequency for trig, rate for exponential
- Lower Bound (a)
- Lower limit of integration
- Upper Bound (b)
- Upper limit of integration
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersFunction Type = 1, Coefficient (c) = 1, Parameter (n) = 2, Lower Bound (a) = 0 = 5 input(s) provided
- Calculate Definite IntegralDefinite Integral0.33333 = 0.33333
Engine last updated . Checked against 6 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does the Upper Bound move the result so much more than the Coefficient does?
For a polynomial integral, the antiderivative scales with the bound raised to the power of Exponent plus 1, while it only scales linearly with the Coefficient. At the calculator's default Upper Bound of 1 and Exponent of 2, that means the bound's influence compounds through an exponent while the coefficient's influence stays a flat multiplier, giving the bound the larger swing for an equivalent percentage nudge.
Why does raising the Exponent lower the Definite Integral at the default settings?
With the Upper Bound sitting at exactly 1 and the Lower Bound at 0, any power of the upper bound still equals 1, so the antiderivative reduces to Coefficient divided by (Exponent plus 1). Growing the Exponent only makes that denominator bigger, which shrinks the quotient — a relationship that would look different at any Upper Bound other than 1.
What's the difference between the Definite Integral and the Absolute Area?
The Definite Integral is a signed quantity: area below the x-axis subtracts from area above it, so the two can partially or fully cancel across the interval. Absolute Area instead sums the magnitude of the curve everywhere in the interval using a separate numerical pass, so it never goes negative and never lets a dip below the axis offset a rise above it.
Are the trigonometric and exponential integrals computed exactly, or approximated?
Both are computed exactly, the same way the polynomial case is: the calculator plugs the Upper and Lower Bound into the standard closed-form antiderivative for sine or the exponential function rather than summing numerical samples. Only the Absolute Area readout relies on a numerical Simpson's-rule approximation, regardless of which function family is selected.
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