6 questions, ~75 seconds. Anchored on Ericsson’s deliberate-practice research.
Deep-work capacity is trainable and has a ceiling — about 4 hours a day even for elite performers. Where are you on that curve?
Deep work capacity is how much full-concentration, cognitively demanding work you can sustain in a day. Research on deliberate practice by Ericsson, Krampe and Tesch-Römer (1993) put the ceiling at roughly four hours a day even for elite performers, and only after years of training. People new to sustained focus manage closer to one hour.
The calculator estimates three numbers for you: your personal ceiling, the capacity realistically available today once your current conditions take their cut, and how much of that you are actually using. The gap between them is the opportunity.
Your personal ceiling starts from Ericsson's ~4-hour limit, scaled to your focus training level. From there the model subtracts four drains, each expressed as a fraction of the ceiling, then adds back a bonus for protective habits such as a defended morning block. A revealed-capacity floor keeps the estimate at or above what you already sustain.
For someone experienced at sustained focus, roughly three to four hours, taken in 60–90 minute blocks with real rest. People new to it typically sustain about an hour. The four-hour figure comes from Ericsson, Krampe and Tesch-Römer's (1993) study of elite performers and is an upper ceiling, not a daily target.
The calculator sets a personal ceiling from your focus training level, then subtracts fractions of it for sleep debt, fragmentation and meetings, missing recovery, and context-switching load. It adds a bonus for protective habits. The result is your realizable capacity, which it compares to the hours you say you currently do.
Sleep below about 7.5 hours measurably degrades prefrontal function — the systems that hold attention on one thing — regardless of motivation (Walker, 2017). The calculator treats sleep debt as a cap the other factors operate under, worth up to 30% of your ceiling.
The ceiling is the most you could sustain if sleep, calendar and recovery were all optimal. Realizable capacity is what is actually available today after those conditions take their cut. The ceiling is raised by training; realizable capacity is raised by fixing conditions.
Your inputs are saved only to your browser's local storage, on your device, so you can revisit the result. Ikuna collects anonymous usage analytics — that the calculator was started and completed, and the resulting utilization band — but not your individual inputs and nothing that identifies you.
This tool is made by Ikuna, a focus-intelligence and context manager for macOS. See all free self-assessments.