The Small Details Behind Expense Categories
Categories look like the simplest part of any expense tracker — a label and an icon, done. In practice they’re one of the parts I’ve rewritten the most, because getting them slightly wrong makes the whole tracker feel like a chore. Here are the small details that actually mattered.
Icons carry more weight than labels
Scanning a transaction list by reading category text is slow. Scanning it by recognising a small coloured icon is almost instant — your eye picks out “food” or “bills” as a shape and colour before you’ve consciously read anything. That’s why every category in My Pocket gets its own icon, not just a text tag.
Colour-coding income vs. expense, not category vs. category
It’s tempting to give every category its own colour, but that turns the transaction list into a rainbow that’s actually harder to parse. My Pocket only colour-codes the one distinction that matters at a glance: red for money out, green for money in. Categories get icons for identity; colour is reserved for direction.
A short list beats a complete list
It would be easy to ship thirty categories to cover every possible purchase. In practice, a shorter list of categories that map to how people actually think about spending — food, bills, transport, and a handful of others — gets used correctly far more often than an exhaustive one, where people either can’t find the “right” category or stop bothering to pick one at all.
Reports only work if entry was honest
The whole point of categorising in the first place is that it feeds the Reports view later — a breakdown of where your money actually goes. That breakdown is only as good as the categorising discipline behind it, which is exactly why the entry step has to stay fast and low-friction. A reporting feature is downstream of a good logging experience, not a separate thing.
None of this is complicated engineering. It’s the kind of detail that’s invisible when it’s right and mildly annoying when it’s wrong — which is exactly the kind of thing worth getting right.
