Why are there two different modulo results?

Languages disagree on the sign of the remainder. The truncated convention (JavaScript, C, Java) gives a remainder with the sign of the dividend a. The floored convention (Python's % and the mathematical "mod n") gives a remainder with the sign of the divisor n, always in the range 0 to |n|. They only differ when exactly one of the numbers is negative.

How accurate is the calculation?

It uses standard arithmetic rounded to ten decimals for display and is exact for integer inputs, which is the usual case for modulo. Division by zero is reported as undefined.

Is my input sent anywhere?

No. The calculator is privacy-first — both numbers stay in your browser and nothing is transmitted to any server.

Modulo Calculator (Remainder)

Find a mod n — both the truncated and floored remainder conventions.

Modulo (remainder) calculator

Compute a mod n and see the remainder under both common conventions: the truncated result used by JavaScript, C and Java, and the floored result used by Python and standard mathematics. The integer quotient is shown too. The two remainders differ only when exactly one of the numbers is negative.

It is privacy-first: all arithmetic happens locally in your browser, so the numbers you enter never leave your device.