Trapezoidal Rule Calculator
Pick a function, set the limits a and b and the number of intervals to estimate the integral.
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
The composite trapezoidal rule approximates a definite integral by splitting the interval [a, b] into n equal-width strips of width h = (b−a)/n, treating each strip as a trapezoid under the curve, and summing their areas: ∫f(x)dx ≈ (h/2)[f(a) + 2f(x₁) + 2f(x₂) + ... + f(b)]. More strips means smaller trapezoids and a closer approximation to the true area.
It's one of the first numerical integration methods taught in calculus and numerical methods courses, and remains genuinely useful whenever a function has no closed-form antiderivative, or when you only have discrete data points (like sensor readings over time) rather than a formula to integrate analytically.
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