OR Calculator - Complete Guide

Bitwise OR calculator performs logical OR operation on binary numbers. Each bit pair is compared: 0 OR 0 = 0, all other combinations = 1. Essential for setting flags, combining bitmasks, and building permission sets.

How It Works

Input two numbers. Calculator converts to binary, aligns bits, and performs OR on each position. A result bit is 1 if EITHER or BOTH corresponding input bits are 1. Only 0 OR 0 produces 0.

Technical Details

OR truth table: 0|0=0, 0|1=1, 1|0=1, 1|1=1. In programming: | operator. Used to: set bits, combine flags, create bitmasks. Result is at least as large as the larger input.

Common Use Cases

1. Setting Flags: Turn on specific bits without affecting others.
   • Example: flags | FLAG_ACTIVE sets the active bit
2. Combining Permissions: Merge multiple permission sets into one.
3. Building Bitmasks: Combine individual bit flags into a mask.
   • Example: READ | WRITE | EXECUTE
4. Default Values: Provide defaults: value | default when value might be 0.

Code Examples

Bitwise OR Operations

// Basic OR
console.log(12 | 10);  // 14
// 1100 (12)
// 1010 (10)
// ----
// 1110 (14)

// Set a specific bit
const setBit = (n, pos) => n | (1 << pos);
setBit(0b1000, 1);  // 0b1010 (set bit 1)

// Combine flags
const READ = 0b001;
const WRITE = 0b010;
const EXECUTE = 0b100;
const permissions = READ | WRITE | EXECUTE;  // 0b111 (7)

// Set flag if condition
function setFlag(flags, flag, condition) {
  return condition ? flags | flag : flags;
}

OR outputs 1 if either input is 1. Use to set bits, combine flags, build masks.

Tips & Best Practices

• OR with 1 sets bits, OR with 0 preserves
• Use for combining flags and permissions
• | is bitwise, || is logical
• Result is at least as large as inputs
• Combine with AND for read-modify-write

Common Mistakes to Avoid

• Confusing | (bitwise) with || (logical)
• Using OR when AND is needed
• Not understanding flag combination
• Operator precedence issues

When to Use This Tool

Use bitwise OR to set specific bits, combine permission flags, build bitmasks, and any operation requiring selective bit setting.

Frequently Asked Questions

How do I set a specific bit?

OR with a mask having that bit set: value | (1 << n) sets bit n. Example: flags | 0x04 sets bit 2 regardless of its previous value.

What is the difference between | and ||?

| is bitwise OR (operates on each bit). || is logical OR (short-circuit boolean). Use | for bit manipulation, || for boolean conditions. In C: 5 | 3 = 7, 5 || 3 = 1 (true).

How do I combine multiple flags?

OR them together: flags = READ | WRITE | EXECUTE. This creates a bitmask with all specified bits set. Works because OR accumulates 1s from all inputs.

Why use bit flags instead of booleans?

Efficiency: 8 flags fit in 1 byte vs 8 bytes for 8 booleans. Easy to combine, store, and transmit. Common in file permissions, network protocols, hardware registers.

Get Started

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Last updated: June 27, 2026