Integral calculator
Find indefinite integrals (antiderivatives) and evaluate definite integrals. Every result is checked by differentiating it before you see it. Works with sin, cos, tan, ln, e^x, sqrt and arctan. Free, no sign-up.
The answer will show up here, written the way you'd write it on the board.
How to use the integral calculator
Type the function with x as the variable and press "Integrate" to get the antiderivative, written as F(x) + C. For a definite integral, tick the box and enter the limits. Write it the way you would in class: x^2 for powers, e^(3x), ln(x), sqrt(x), sin(x)^2 or sin^2(x), arctan(x). Use a point for decimals (0.5).
Before showing you an antiderivative we differentiate it and compare the result with your function at several points. If they don't match, you don't see it. For definite integrals we also check that the function is continuous on the interval and compute the value numerically a second way, so the Fundamental Theorem of Calculus answer, F(b) − F(a), is backed up by an independent number.
Examples worked out with this calculator
- Basic antiderivative: and
- Integration by parts:
- Partial fractions:
The calculator shows the answer, not the working. If your homework asks for the method (which u to pick in a u-substitution, how to split into partial fractions), the step-by-step button sends the problem to PhotoExamAI. To check an antiderivative by hand, differentiate it with the derivative calculator: you should get back the function you started with. More free calculators are in the study tools section.
Frequently asked questions
What kinds of integrals can it do?
The ones you meet in high school calculus and first-year college calculus: basic antiderivatives, integration by parts, rational functions (using partial fractions), trig integrals and some u-substitutions. Every antiderivative is checked by differentiating it: if the derivative doesn't match your function, we don't show it.
Why does it sometimes say it couldn't find the integral?
Because we'd rather not give you an answer we haven't checked. Some functions, such as e^(x^2) or sin(x)/x, have no elementary antiderivative, and there are others the engine can't handle. In that case you can ask PhotoExamAI for a worked solution, or switch to a definite integral, which is always evaluated numerically.
Do I need to add + C?
The calculator adds it for you. An indefinite integral is a whole family of antiderivatives that differ by a constant, so every answer is written as F(x) + C. For a definite integral the constant cancels out in F(b) − F(a), so it isn't shown.
How do I evaluate a definite integral or find an area?
Tick "Definite integral" and type the limits (pi, e and fractions are fine; use a point for decimals, as in 1.5). If the function is continuous on the interval you get the exact value when it's a recognisable number (like π/4) and always the decimal value. For the area between the curve and the x-axis, split the interval wherever the function changes sign.
Why is there an absolute value in ln|x|?
Because the antiderivative of 1/x is ln|x| + C, which also works for negative x. The absolute value only appears when the argument can be negative where the function is defined. That's why ∫2x/(x²+1) dx comes out as ln(x²+1) + C, with no bars.
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