Calculate definite integrals securely online. Features mathematical syntax parsing and high-accuracy numerical approximation directly in your browser. No data stored.
Definite Integral Calculator
Evaluate definite integrals numerically directly in your browser. Supports trigonometric functions, logarithms, and standard algebraic notation.
Supported Syntax
^for exponents (e.g.,x^2)*for multiplication (e.g.,2*xor2x)/for divisionsqrt(x)for square rooteandpias constants
Functions
sin(x)cos(x)tan(x)log(x)(natural)log10(x)abs(x)
How the Integral Calculator Works
When studying calculus or working in engineering, evaluating complex definite integrals by hand can be tedious and prone to human error. Our Integral Calculator provides instant, high-accuracy estimations using advanced numerical methods.
Unlike many other calculators that rely on heavy server-side processing—which can be slow and computationally expensive—this tool parses your mathematical expression and evaluates the function entirely within your browser using JavaScript.
Simpson's 3/8 Rule
To calculate the area under the curve, this tool implements Simpson's 3/8 Rule. This is a highly accurate method for numerical integration that approximates the required function using cubic parabolas rather than standard straight lines or flat rectangles (like the Riemann sum).
Under the hood, we divide your interval $[a, b]$ into thousands of microscopic sub-intervals to ensure precision up to several decimal places.
Safe & Private
Because the integration engine runs directly in the client (your device), your equations are never transmitted over the internet or saved to a database. You can safely calculate proprietary engineering formulas or offline academic problems without worrying about data tracking.
Frequently Asked Questions
Does this solve indefinite integrals?
No. This tool is designed strictly for evaluating definite integrals (finding the exact numerical area between two defined bounds, $a$ and $b$). It does not perform symbolic algebra to return an overarching equation with $+C$.
What happens if the function is undefined?
If you attempt to integrate over a vertical asymptote (like evaluating $1/x$ across $0$), the numerical engine will catch the divergence and return an error message to let you know the result is undefined or divergent.
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
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