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Number Base Converter

Convert numbers between decimal, hexadecimal, binary, and octal instantly online. Free number base converter tool. No signup required.

Decimal Input

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Positional numeral systems represent the same integer value using different digit sets and place-value bases. Decimal (base 10) is the standard human notation; binary (base 2) is how digital circuits store and process data; hexadecimal (base 16) compactly represents binary data; and octal (base 8) maps cleanly onto 3-bit groups used in Unix file permissions.

These bases appear constantly in low-level computing: memory addresses and color codes in hex, CPU instruction sets and network masks in binary, Unix chmod permissions in octal, and all human-readable quantities in decimal. Developers switch between them when reading assembly output, writing hardware drivers, inspecting network packets, or specifying bitmask flags.

This tool accepts input in any of the four bases, auto-detects or lets you select the source base, and instantly outputs all four representations. Each row has its own copy button, so you can grab just the hex or just the binary value without selecting and copying manually.

Common Use Cases

Reading CPU disassembly and opcodes

Disassemblers like IDA Pro and Ghidra display memory addresses and instruction opcodes in hexadecimal. Converting a hex address such as 0x1A3F to decimal confirms whether it falls within a specific memory segment range when cross-referencing a linker map file or debugging a segfault.

Setting Unix file permissions with chmod

Unix chmod accepts octal permission codes: chmod 755 grants rwxr-xr-x. Converting 755 from octal to binary (111 101 101) makes each permission bit visible, helping developers verify that a deployment script grants the correct combination of read, write, and execute bits.

Manipulating bitmask flags in embedded C

Embedded firmware uses bitmask registers where each bit controls a hardware feature. Converting the decimal constant 68 to binary (01000100) immediately shows which bits are set, making it straightforward to apply |= or &= ~ operations without manually counting bit positions.

Verifying CSS and design token hex colors

CSS colors like #FF6B35 are hex-encoded RGB triples. Converting each two-digit hex component to decimal (R=255, G=107, B=53) allows you to cross-check a design token's hex value against the RGB values exported by Figma or Sketch to confirm they refer to the same color.

How to Use the Number Base Converter

  1. Select the input base using the Dec / Hex / Bin / Oct toggle.
  2. Enter your number in the input field.
  3. All four representations appear instantly below.
  4. Click Copy next to any row to copy that value.
  5. Use Load Example to see a sample conversion (255 in decimal).

Common Number Systems