Bit Field Packer Calculator

About this calculator

A bit field packs several small integer values into contiguous groups of bits within one larger integer, so that a single 32-bit or 64-bit word can hold, say, a 5-bit value, an 8-bit value, and a 3-bit value all at once instead of using a separate variable — and separate memory — for each. This calculator takes up to three values with their bit widths, shifts each into its position, ORs them together, and shows the combined result in decimal, hexadecimal, and binary.

Bit-field packing is everywhere in low-level programming: hardware peripheral configuration registers on microcontrollers assign specific bit ranges to specific settings, network protocol headers (like IPv4’s version/IHL byte or TCP flags) pack multiple fields into a few bytes to minimize overhead, and graphics formats like RGB565 pack red, green, and blue channels into a single 16-bit pixel value. Embedded systems and driver developers use exactly this kind of packing to read and write hardware registers correctly.