Math

Programmer Calculator

Binary, Octal, Decimal, and Hex at a Glance

This programmer calculator mimics the experience of the Windows Calculator or macOS Calculator in programmer mode. Enter a value in any base and instantly see all four common representations side by side.

Number Base Conversion Tips

Click to show tips

Try an Example

Pick a scenario to see how the calculator works, then adjust the values

ASCII Letter A

Convert the ASCII code for uppercase A (65) across all bases.

Key values: Decimal 65 · Binary 1000001 · Hex 41

Byte Maximum

The largest value a single byte can hold (255).

Key values: Decimal 255 · Binary 11111111 · Hex FF

Hex Color Code

Convert a common hex color code (deep sky blue) to other bases.

Key values: Hex 00BFFF · Decimal 49151 · Binary nibbles

Documentation

This calculator is also known as Programmer Calculator.

Read the complete guide

Why Programmers Need Multiple Bases

Code and data are stored in binary, displayed in hex (compact), and input in decimal (human-readable). Switching fluently between these is essential for debugging, inspecting memory, and understanding data structures.

Examples

Debug a Memory Address

Inspect the hex address 0xDEAD in binary.

D=1101, E=1110, A=1010, D=1101. Binary: 1101111010101101.

Key takeaway: 0xDEAD = 57005 decimal = 1101111010101101 binary.

Check a Subnet Mask

Verify that 255.255.255.0 corresponds to a /24 prefix.

255 = 11111111 in binary (8 bits all set). A /24 has 24 contiguous 1s.

Key takeaway: Each octet of an IP subnet mask translates to 8 binary digits.

RGB Color Channel

What is decimal 128 in hex? (50% brightness in RGB).

128 / 16 = 8 R 0. Hex: 80.

Key takeaway: 128 decimal = 0x80, representing ~50% in an 8-bit RGB channel.

Programmer Calculator Tips

Get the most out of this tool:

Use 0x prefix for hex values, 0b for binary, 0o for octal
Use the bit-level view to inspect individual bits and nibble groups
Follow the step-by-step conversion to understand division and multiplication algorithms

Frequently Asked Questions about Programmer Calculator

What is the difference between this and a scientific calculator?

A programmer calculator focuses on base conversions and bitwise operations, while a scientific calculator handles trigonometry, logarithms, and advanced math functions.

What are common prefixes for different number bases in code?

0b or 0B for binary (e.g. 0b1010), 0o or 0O for octal (e.g. 0o755), 0x or 0X for hexadecimal (e.g. 0xFF). Decimal has no prefix. These prefixes are supported by JavaScript, Python, C, and many other languages.

Why do programmers use hexadecimal instead of binary?

Hexadecimal is a compact representation of binary: each hex digit represents exactly 4 bits. So instead of writing 11111111 (8 binary digits), you write FF (2 hex digits). This makes memory addresses, color codes, and byte values much easier to read.