About the Inequality Calculator
Solve linear and quadratic inequalities in x (<, ≤, >, ≥) and get the answer in interval notation.
Also known as: solve inequality, inequality solver, interval notation, linear inequality.
How to use this calculator
- Enter inequality.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Find where the expression equals 0, then test each interval between the critical points
Worked example
Using the values pre-filled in the calculator above:
- Inequality: x^2 - 5x + 4 <= 0
the calculator returns:
- Solution: [1, 4]
- Critical points: 1, 4