StackCalc

This super simple mod simply allows you to quickly calculate item quantities in stacks.

To use it, open chat and type your number and add "s" to the end of it (e.g 1234s) and then simply press the tab key. For larger numbers you can also type "sb" and that will calculate shulker boxes as well. For example "12345sb" will become "7 (Shulker Boxes) + 3 (Stacks) + 57 (Items)". There is also a double chest calculator if you care. Use it the same way "dc"

"1234s" -> TAB -> "19 (Stacks) + 18 (Items)"

"12345sb" -> TAB -> "7 (Shulker Boxes) + 3 (Stacks) + 57 (Items)"