How many categories should you use to log your day?

You open a fresh entry and before you have written a single word, there is a decision to make: which category. Too many options and you hesitate over a colour instead of writing the line. Too few and everything lands in the same bucket, and a bucket with everything in it tells you nothing when you look back. The right number is smaller than most people guess, and it is decided by what you will actually want to read later, not by how detailed your life happens to be.

Too many categories reintroduce the tax you were trying to avoid

It is tempting to give every new thing its own category the moment it shows up: "Freelance — Client A", "Freelance — Client B", "Gym — upper body", "Gym — running". Each one feels reasonable on its own. Together they turn a five-second habit into a small filing decision every time you write, which is exactly the friction that made a timer feel like a job in the first place. The category picker was supposed to be the fast part.

It also breaks the thing categories are for. A summary made of thirty thin slices is not readable at a glance — you cannot see a proportion in thirty slivers of colour, only a blur. The whole point of grouping was to let a pattern show up without you having to count anything.

Too few categories hide too much

The opposite failure is quieter and just as common: one catch-all category — "Life", "Misc", "Other" — that absorbs anything that does not obviously belong somewhere else. It feels efficient in the moment. Months later, the summary shows one enormous bar labelled Life and a few thin ones around it, and the enormous bar tells you nothing, because everything from a doctor's appointment to a long walk to a difficult phone call is sitting inside it undifferentiated. A category that contains everything carries the same information as no category at all.

What a category is actually for

A category is not there to classify a moment precisely. It exists so that, months from now, a glance at a week or a month shows you a proportion — this stretch was mostly one colour, that stretch had almost none of another — without you having to reread every line to notice it. The test for whether a category earns its place is not "is this technically the right label" but "will grouping things this way ever show me something I would not have otherwise seen."

Pick domains, not projects

A category that survives a year describes a domain of your life, not whatever is currently happening inside it. Work outlives whichever project you are on this quarter. Health outlives whichever habit you are trying this month. Social outlives whichever group of people you happen to be closest to right now. A category built around March's preoccupation — a specific client, a specific class, a specific goal — is usually dead by June, and a dead category just sits in the list as one more thing to skip past every time you write.

• Durable: work, study, exercise, food, social, health, home, money, travel, fun.
• Likely to expire: a single client's name, a single course, a single event you are training for.

If a name would only make sense to you for the next few months, it probably belongs inside the note itself — write the client's name or the course title in the line, where the earlier point about specific nouns already covers it — and let the category stay broad enough to still make sense next year.

A number to aim for

Somewhere between six and twelve tends to hold up. Fewer than six and categories start swallowing things that do not really belong together, because there is nowhere better to put them. More than twelve and choosing one becomes its own small chore, and a chore attached to every single entry is the fastest way to make the whole habit feel heavier than it needs to be.

When it is actually worth adding one

Add a category when you notice yourself forcing the same kind of entry into one that does not quite fit, more than once or twice, and the thing behind it looks like it is going to keep being part of your life rather than fade out in a few weeks — a real return to some part of your health, a course of study you are actually committing to, not a house move that will be finished by autumn.

When it is worth waiting

Most temptations to add a category arrive right after something new happens, which is exactly when it is hardest to tell whether the thing will last. Give it a month inside an existing category first. If it turns out to deserve its own colour, you will know by then, and you will have saved yourself the smaller chore of deleting one that did not.

TimeMap ships with a small set of built-in colour categories along these lines — work, study, exercise, food, social, health, life, finance and travel among them, with one left over for anything that genuinely does not fit — so nobody has to invent a taxonomy before they can write a first line. Use what is there, adjust it once if something is clearly missing, and then stop deciding. The only thing that should take any thought at the moment of writing is what actually happened.