Bitwise operations work on each pair of bits independently. OR is used for setting flags and permission bits, combining options into a single number and merging bit masks. Programmers meet it in C, Java, Python and JavaScript as the | operator.
How to use the Bitwise OR Calculator
- Representation
- Number format
- Number 1
- Number 2
- Operation
Everything is calculated in your browser, so results appear instantly and nothing you type is sent to a server.
How it works
Choose the bit width (representation) and the input format, then enter both numbers. They are padded to the chosen width, combined bit by bit and the result is shown in every common base. With a fixed width, the signed value uses two’s complement.
Tips
- Choose a bit width (8, 16, 32 …) so negative numbers and overflow are shown correctly.
- Group binary digits in fours – each group is one hexadecimal digit.
- The leftmost bit is the sign bit in two’s complement.
- Everything is calculated exactly with whole-number arithmetic in your browser.
Common mistakes to avoid
- Reading a signed number as unsigned (or the reverse).
- Forgetting to add 1 when forming a two’s complement.
- Dropping leading zeros that matter for a fixed bit width.
Formula
a OR b is 1 when at least one bit is 1; truth table: 0 0 → 0, 0 1 → 1, 1 0 → 1, 1 1 → 1
Worked example
Inputs — Representation: 8-bit; Number format: Binary; Number 1: 1011; Number 2: 0110; Operation: OR.
Results — Result (binary) = 0000 1111; Result (decimal, unsigned) = 15; Result (decimal, signed two's complement) = 15; Result (octal) = 17; Result (hexadecimal) = F; Bit by bit = 0000 1011
OR 0000 0110
─────────
= 0000 1111.
Key terms
- Bit
- A binary digit, 0 or 1.
- Bit mask
- A pattern of bits used to select or change other bits.
Frequently asked questions
What does bitwise OR do?
It compares two numbers bit by bit: a OR b is 1 when at least one bit is 1.
Why choose a bit width?
Operations like NOT, NOR and the signed value depend on how many bits the number has.
Can I enter decimal numbers?
Yes – choose Decimal as the number format.
What is the difference between bitwise and logical OR?
Logical operators treat whole values as true/false; bitwise ones act on every bit separately.
What formula does the Bitwise OR Calculator use?
a OR b is 1 when at least one bit is 1; truth table: 0 0 → 0, 0 1 → 1, 1 0 → 1, 1 1 → 1.