Int to Leading String

Int to Leading String takes a number and pads it with leading zeros so it becomes a fixed-width string. 7 with a minimum digit count of 4 comes out as "0007". It sounds like busywork until the moment your saved files refuse to sort properly - at which point it becomes the most important node in the workflow.

Why you'd reach for it

The classic failure: you're saving frame_1.png, frame_2.png … frame_10.png, and your file browser sorts them as frame_1, frame_10, frame_2. That's not a bug, that's lexicographic sorting - and it's why every production pipeline pads numbers. This node turns your frame counter into frame_0001, frame_0002, so filenames sort the way your eyes expect.

It's also handy for building string identifiers with a stable format: seed values, iteration numbers, batch IDs that need to be a consistent length for downstream parsing.

How it works

The function zero-pads the absolute value to min_digit_count digits, then re-attaches the minus sign if the number was negative. So -5 with a count of 4 becomes "-0005", not "000-5". Padding happens on the digits only - the sign never eats a character slot.

The inputs that matter

• integer - the number to convert. Full int32 range, defaults to 0.
• min_digit_count - the minimum number of digits. Defaults to 1 (no padding at all), and can go up to 20. A count of 3 makes 42 become "042".

One output:

• string - the padded result. Feed it into a String Combiner or directly into a Save node's filename field.

Installing it

Part of the TinyBee pack. ComfyUI Manager → Install Custom Nodes → search "ComfyUI-TinyBee", install, restart. Manual route:

cd ComfyUI/custom_nodes
git clone https://github.com/TinyBeeman/ComfyUI-TinyBee

You'll find it under 🐝TinyBee/Casting in the node menu. It uses only the Python standard library, so there's no dependency wrangling for this one.

Common issues

Two things trip people up. First, if min_digit_count is smaller than the number of digits in your number, nothing is cut off - 15000 with a count of 4 stays "15000". The count is a floor, not a ceiling. Second, the default of 1 means no padding happens until you change it, which catches a lot of people who assume the node pads by default. Set the count to how many digits you want the final filenames to have, and it'll sort correctly every time.