About the Definite Integral Calculator
Evaluate definite integrals of any function between two limits using adaptive Simpson integration — area under a curve.
Also known as: area under curve, definite integration, integral from a to b, integrate between limits.
How to use this calculator
- Enter f(x), lower limit a, upper limit b.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
∫ₐᵇ f(x) dx = F(b) − F(a)
Worked example
Using the values pre-filled in the calculator above:
- f(x): exp(-x^2)
- Lower limit a = 0
- Upper limit b = 1
the calculator returns:
- ∫ from 0 to 1: 0.746824132812
- Total (unsigned) area: 0.7468241328
- Average value of f: 0.7468241328