Factorial Calculator
Calculate the factorial (n!) of any integer from 0 to 170, free and instant, right in your browser.
Type in a whole number and get its factorial instantly, handy for probability homework, permutation and combination problems, or just settling an argument about how fast 20! grows.
How to use it
- Enter a non-negative integer
- Get n! calculated instantly
- Copy the full result, digits and all
Frequently asked questions
- How large a number can I compute?
- The calculator handles very large factorials (into the hundreds) by using arbitrary-precision math in your browser, so you'll get the exact full digit string instead of a rounded scientific-notation approximation.
- What is 0! and why isn't it 0?
- 0! equals 1 by definition. It's the empty product, and that convention keeps formulas like combinations and permutations working correctly for zero items.
- Can I use decimals or negative numbers?
- No, standard factorial is only defined for non-negative integers (0, 1, 2, ...). For non-integer inputs you'd need the Gamma function, which this calculator doesn't compute.
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Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
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No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
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Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.