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Online Modulo Calculator
Find a mod b — the remainder after division — for any two numbers, with an always-non-negative result you can copy in one click.
Modulo
1
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What Is This Tool?
The Modulo Calculator finds a mod b, the remainder left after dividing the first number by the second. You enter a value for a and a value for b, click Calculate, and see the result — for example, 5 mod 2 is 1. It always returns a non-negative remainder, so even a negative input like -5 mod 2 gives 1, and it lets you copy the answer to your clipboard with one click.
How to Use This Tool?
- Enter the dividend in the field marked a.
- Enter the divisor in the field marked b.
- Click the Calculate button to see a mod b.
- Click the copy icon to copy the result to your clipboard.
Key Features
- Calculates a mod b, the remainder after dividing a by b.
- Always returns a non-negative result, even when a is negative.
- Accepts whole numbers as well as decimal values for both inputs.
- Flags a zero divisor, since modulo by zero is undefined.
- Includes a one-click copy button to place the result on your clipboard.
Examples
- 5 mod 2 equals 1.
- 10 mod 3 equals 1.
- -5 mod 2 equals 1, because the result is kept non-negative.
- 7 mod 7 equals 0.
Common Use Cases
- Checking whether a number is even, odd, or divisible by another.
- Wrapping values around a range, such as hours on a 12-hour clock.
- Distributing items evenly and finding the leftover amount.
- Verifying remainder results from programming or spreadsheet formulas.
- Teaching or practicing remainder and modular arithmetic concepts.
Tips & Best Practices
- Enter the number being divided as a and the number you divide by as b.
- Use a non-zero value for b, since dividing by zero is undefined.
- Expect a non-negative result, which may differ from a programming language's sign rules.
- Use whole numbers for standard modular arithmetic; decimals are also supported.
- Copy the result directly from the tool to avoid transcription mistakes.
Limitations
- Calculates one a mod b operation at a time, not a list or batch.
- The divisor b cannot be zero, which triggers an error.
- Always returns a non-negative remainder, which differs from some languages' sign conventions.
- Very large or highly precise numbers are subject to digital precision limits.
Frequently Asked Questions
- What does the modulo operation do?
- It returns the remainder left after dividing a by b; for example, 5 mod 2 is 1.
- Why is -5 mod 2 equal to 1 here?
- The tool always returns a non-negative remainder, so the result lands between 0 and b.
- Can b be zero?
- No. Modulo by zero is undefined, so a zero divisor shows an error message.
- Does it work with decimals?
- Yes. Both inputs accept decimal values, not just whole numbers.
Key Terminology
- Modulo
- An operation that returns the remainder after one number is divided by another.
- Dividend
- The number being divided, entered as a in this tool.
- Divisor
- The number you divide by, entered as b, which must not be zero.
- Remainder
- The amount left over after dividing one number by another.
- Non-negative result
- A remainder kept at zero or above, so it falls between 0 and b.