bit length

"Bit length" asks a question you rarely think to ask: how many bits does it take to represent this integer? The answer is 5 for 17, 8 for 255, and 0 for 0. It's the companion to the pack's bit count node, and like its sibling it's the sort of utility that sits unused for months and then becomes the missing piece of a byte-packing or bitmask workflow.

What it does

It returns the minimum number of bits needed to hold the value's binary representation, excluding the sign and leading zeros. 10 is 1010 - four bits, so bit length 4. 255 is 11111111 - eight bits. The function is Python's int.bit_length(), which handles the edge cases sensibly: 0 returns 0 (no bits needed), and negative numbers return the bit length of their absolute value (so -10 also returns 4 - the sign isn't counted as a bit).

Why bother? If you're building a byte-packing step, bit length tells you the minimum length your to bytes conversion needs. If you're probing a value parsed from raw data, it tells you how wide the field actually is. It's also a quick "how big is this number" sanity check that's cheaper than fiddling with logarithms.

Inputs and outputs

• int_value - INT, default 0. The integer to measure.
• Output INT - the number of bits required, sign and leading zeros excluded.

One input, one output, no settings.

Install

Ships in the Basic data handling pack. Via ComfyUI Manager: search "Basic data handling", install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/StableLlama/ComfyUI-basic_data_handling

then restart ComfyUI. Pure Python, no dependencies, no model files.

Where it pairs well

The classic combo is bit length feeding to bytes: figure out how wide the value is, then convert it with a length big enough to hold it. Unlike bit count (which needs Python 3.10+ for int.bit_count()), bit_length() has existed since Python 2.7, so this one is safe on any Python ComfyUI will realistically run. The only "surprise" is that 0 returns 0 - a value with no bits - which trips people up exactly once when they're computing byte lengths and forget to add padding.