Plan sustainable deep work capacity and how long a project will take.
Sustained deep work capacity tops out around four hours a day for most people, and planning above that produces schedules that slip. Applying a sustainability factor to the target gives a figure that survives contact with a real week. Project estimates built on eight productive hours a day overrun by roughly double, because the other hours go to shallow work that is real but not deliverable output.
Deep Work Time
Weeks = project deep work hours ÷ (achievable daily deep hours × working days)
Weeks = project deep work hours ÷ (achievable daily deep hours × working days) Sustained deep work capacity tops out around four hours a day for most people, and planning above that produces schedules that slip. Applying a sustainability factor to the target gives a figure that survives contact with a real week.
Project estimates built on eight productive hours a day overrun by roughly double, because the other hours go to shallow work that is real but not deliverable output.
This calculator takes 5 inputs: Deep work hours targeted per day, Working days per week, Deep work hours the project needs, Share of targeted deep work actually achieved, Shallow work hours per day. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.