Time Calculators

A time calculator is a structured guess. You describe the job in a few numbers, and it returns a duration you can put in a calendar. It will not be exact. It is there to stop you from writing "one hour" on something that has never once taken an hour.

Why the first estimate is nearly always short

Most estimates describe the clean version of a task: you start on time, everything you need is already open, nobody interrupts, and you stop the moment the work is done. Real work has a beginning and an end attached. Finding the file. Reading back yesterday's work. The message halfway through. Saving, filing, and telling someone it is done.

So there are two fixes, and they are boring. Estimate the whole trip rather than the main leg, setup and clean-up included, then add a buffer on top.

How much buffer to add

A quarter to a third on top of your estimate is a sensible starting point. Push it higher for work you have never done, work that waits on somebody else, or anything with a hard start time straight after. Push it lower only for work you have done many times and timed.

Buffer is not padding you have to justify. It is the part of the task you keep forgetting to write down.

What changes the number, by type of work

Meetings. The meeting itself is often the shortest part. Reading the agenda, pulling up the numbers you will be asked about, and writing up decisions afterwards can easily match the length of the meeting. Book preparation time separately instead of hoping it fits in the gap before.

Email and inbox processing. Do not estimate per message. Estimate the session. Most of an inbox is sorted quickly; the time goes into the handful of replies that need a decision. Count those separately and treat everything else as one block.

Content and creative work. Research, drafting, and editing behave like three different jobs. Editing frequently takes as long as drafting did, and a draft that stalls is usually missing research rather than willpower. Estimate the three stages separately.

Code review. Time scales with the number of areas touched, not the number of lines. A large but repetitive change reads fast. A small change across four unfamiliar files does not. Splitting a review across the day costs extra, because you reload the context each time.

Study sessions. Reading, practising, and testing yourself are not interchangeable, and reading is the fastest of the three. Plan the session around what you want to recall afterwards, and include the few minutes at the start spent working out where you left off.

Workouts. The session on your plan is rarely the session in your calendar. Add travel, changing, warm-up, cool-down, and a shower. A forty minute workout can be a ninety minute block.

Meal prep. Shopping, chopping, cooking, cooling, portioning, and washing up. Cooking several things at once does not halve the total, because the oven, the hob, or your own attention becomes the limit. Cooling and packing are the steps people leave out.

Reading. Your pace changes completely with the material. Fiction, a textbook, and a contract are three different speeds. Time yourself on ten pages of the actual thing before estimating the whole.

The calculators

Make the estimates yours

Write your estimate down before you start, then write the actual time next to it when you finish. Do that for a couple of weeks and you have something better than any calculator on this page: a record of how long your own work takes.

Once you have a number, the next question is where it goes in the day. That is what the schedule builders are for, and if you would rather have the structure on paper, the printable planners cover the same ground offline.