Dividing the hours you have left by the days you have left is the calculation that blows up deadlines, because it assumes you perform at one hundred percent the whole time. This calculator folds in your real focus and gives you two numbers: calendar hours and real hours. Free, no sign-up, everything stays on this device.
Formula: real hours per day = total hours ÷ (focus ÷ 10) ÷ workable days. It is the app's weighted-hours formula, read backwards.
The classic estimate goes like this: sixty hours left, twenty days left, so three hours a day. It sounds reasonable, which is why almost everyone does it. The problem is that the number describes hours of work produced, while the only thing you can actually put in a calendar is hours of calendar time, and the two almost never match.
Nobody performs at one hundred percent. Notifications, context switches, the twenty minutes it takes to get back into a file after an interruption, evening fatigue: none of that disappears because you wrote three hours in your calendar. If your average focus is seven out of ten, producing sixty hours of real work means sitting there for roughly eighty-six hours. The original estimate was off by twenty-six hours, nearly a third, and you find out in the final week.
That is why this page gives you two numbers instead of one. Calendar hours are the optimistic estimate, the one you do in your head. Real hours are what you actually have to block out. The second number is the one that decides whether the deadline is reachable.
FocusSea is built around an idea called the weighted hour. At the end of every work session you rate your concentration from 1 to 10, and the session is worth minutes times focus divided by ten. Ninety minutes at focus 6 are worth fifty-four minutes of real work. Sixty minutes at focus 10 are worth sixty.
That is exactly the calculation you just ran above, applied to a single block of work instead of a whole project. This page runs it forwards to make a prediction; the app runs it backwards to measure what actually happened.
The difference is that here your focus is an estimate, a number you pick. In the app it becomes data: session after session it tracks weighted hours against calendar hours, and after a week or two you know what your real focus is rather than what you imagine it to be. At that point you stop guessing the divisor, because you know it, and the prediction for the next deadline becomes something you can trust.
Plenty of people discover they are below their own estimate. The useful part is not the disappointment, it is finally being able to plan against a real number.
FocusSea is a timer that asks how concentrated you were at the end of each session and turns that into weighted hours. After a few days the divisor on this page is no longer a guess, it is your own data.
Try it free →Use 7. It is the reasonable estimate for someone working in a normal environment, with some interruptions but no chaos. Use 5 or 6 if you work in an open space or with your phone always on, and 8 or 9 only if you have already measured genuinely protected sessions. Above 9 is almost always optimism.
Because total hours are hours of work produced, while real hours per day are hours of calendar time to block out. At focus 7 out of 10 it takes roughly ten hours in the chair to produce seven hours of work. That is not pessimism, it is why plans based on simple division fall apart.
The page counts calendar days from today to the deadline, then takes the share matching the days per week you chose. With five days out of seven, twenty calendar days leave fourteen workable ones. We do not ask which weekdays, because it barely changes an estimate and would make the form heavier.
No. The whole calculation runs in your browser, none of your numbers are sent anywhere, and reloading the page leaves nothing behind.
This page makes a prediction from a focus level you estimate. The app does the measuring: it logs every session with its focus rating, accumulates weighted hours and shows your real focus over time. You can use the page on its own, but the prediction will only ever be as good as the estimate you feed it.
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