Prime Number Checker
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter a number.
- Press Calculate.
How it works
Tests whether a number is prime — divisible only by 1 and itself — by checking for factors up to its square root.
Worked example
7. is prime; 8 is not.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.