This integral calculator finds the indefinite integral, or antiderivative, of a function of x. Integration is the reverse of differentiation: where a derivative tells you how fast something is changing, the integral builds the original quantity back up from its rate of change, which is how you turn velocity into distance or a rate of flow into a total volume. Because the derivative of any constant is zero, an indefinite integral is never unique, so the answer always carries a constant of integration written plus C. You enter a function using x as the variable, with a star for multiplication and a caret for powers, for example 3*x^2 + 2*x or exp(2*x), and the calculator returns its antiderivative. It handles the cases that come up most in study and everyday calculus: polynomials of any degree using the power rule, one over x giving the natural logarithm, exponentials, and sine and cosine with a linear argument. For more unusual functions, where a neat antiderivative may not exist in elementary form, the companion definite integral calculator gives the numeric area under the curve between two limits instead. The result here may be shown unsimplified but is always correct, since you can differentiate it to recover your original function. Enter a function to see its integral straight away.
Use * for multiply and ^ for powers. Handles polynomials and standard forms (powers, 1/x, exp, sin, cos with a linear argument). For other functions, try the definite integral calculator. Estimate only.
The calculator reads your function into an expression tree and integrates term by term. It reverses the power rule for powers of x, returns the natural log for one over x, and divides by the inner slope for an exponential, sine or cosine with a linear argument. Constant factors are taken outside the integral. The constant of integration plus C is always added.
For 3*x^2 + 2*x, reversing the power rule on each term gives x^3 + x^2, plus the constant of integration C. Differentiating x^3 + x^2 returns 3*x^2 + 2*x, confirming the result.
If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.
Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.
All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.
Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.
Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.
Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.
All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.
About & trust: Why Calculate is NZ's most comprehensive · By the Numbers · How we compare · Editorial standards · How we keep data current · NZ finance glossary · Research & data · Financial literacy NZ · About · Privacy policy · Terms of use
Reviewed and maintained. Last reviewed 2026-06-07 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.
© 2026 Calculate.co.nz. All rights reserved. Building free NZ calculators since 2011.