What is the Inequality Calculator?

Solve linear and quadratic inequalities step by step. Enter your inequality expression and get the solution set with a number line representation. Free online inequality solver.

Is the Inequality Calculator free to use?

Yes. The Inequality Calculator is free to use on Calculate.co.nz, with no sign-up, paywall or account required.

Is the Inequality Calculator made for New Zealand?

Yes. It is hosted on Calculate.co.nz for New Zealand students. The calculations use standard algebra that works the same way anywhere, so no country-specific rules or rates are involved.

Inequality Calculator

This calculator solves quadratic and linear inequalities written in the form ax squared plus bx plus c, compared against zero, and shows the full working rather than just a final answer. You enter the coefficients a, b and c and choose whether you want the expression to be less than or greater than zero, then press Solve it. If a is zero, the tool recognises a straightforward linear inequality and returns the answer directly, correctly reversing the sign whenever it divides by a negative number. For a genuine quadratic, it first finds the roots using the quadratic formula shown above the calculator, converts the expression into factored form, and builds a sign table tracking whether the function is positive, negative or zero across the intervals either side of each root. From that table it states the solution set in set notation, such as the range between the two roots or the two outer regions beyond them, and plots a graph of the curve with the section where your inequality holds marked out, so you can see the answer as well as read it. Use it to check your own working on a quadratic inequality, to follow the reasoning behind the roots and sign changes step by step, or to see how adjusting a coefficient shifts the roots and the resulting solution range.

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Reviewed and maintained. Last reviewed 2026-07-27 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.

Inequality Calculator

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