Deep Work Time Audit, Interruption Cost & Focus Ratio

Deep work time and the cost of interruptions: how it is estimated

The tool subtracts meetings and email from the working day, then 0.2 h (12 minutes) per interruption, to estimate deep focus time. With an 8-hour day, 4 hours of meetings and email and 14 interruptions, 1.2 hours of deep work remain, 15% of the day.

The four indicators and their formulas

• Deep work: max(0.5; day − meetings − email − 0.2 × interruptions), rounded to 0.1 h. The card turns green from 40% of the day.
• Shallow work: meetings + email and admin.
• Refocus loss: the hours removed from deep work, i.e. 0.2 h × interruptions (12 minutes each), within the time left after meetings and email, minus the 0.5 h deep work minimum.
• Annual cost: fragmented hours × 225 days × hourly cost, where fragmented hours (the day minus deep and shallow work) equal the refocus loss.

All indicators use the same 0.2 h per interruption: the displayed loss matches the hours removed from deep work.

Example

An 8-hour day, 2.5 h of meetings, 1.5 h of email, 14 interruptions, €65 per hour. Shallow: 4 h (50%). Deep work: 8 − 4 − 2.8 = 1.2 h (15%). Fragmented hours: 2.8 h. Refocus loss: 14 × 0.2 = 2.8 h, the same hours as the fragmented share. Annual cost: 2.8 × 225 = 630 h, or €40,950. With 5 interruptions and 2 h of meetings and email, deep work rises to 5.0 h.

Limits

The 23 minutes come from a field study: interrupted work was resumed on average 23 minutes 15 seconds later, often after switching to other tasks in between, so that time is not all lost. The 225 days (45 five-day weeks) and the 0.5 h minimum are the tool’s own choices. Treat the result as an order of magnitude for discussing how work is organised.

Sources and dates: Gallup Business Journal, interview with Gloria Mark (UC Irvine), published 8 June 2006: interrupted tasks resumed on average after 23 min 15 s (checked 14/10/2026).

Frequently Asked Questions

How long does it take to refocus after an interruption?

The most quoted figure comes from Gloria Mark’s research at UC Irvine: interrupted work was resumed on average 23 minutes 15 seconds later. That time is not all lost: the tool counts 12 minutes (0.2 h) of lost deep work per interruption, in all its indicators.

How does the tool calculate deep work time?

It starts from the length of the day, subtracts meetings and email, then 12 minutes per interruption. The result never drops below 0.5 h.

How is the annual cost of distraction estimated?

It multiplies fragmented hours (12 minutes per interruption, taken from deep work) by 225 days and your hourly cost. With 14 interruptions, 4 h of meetings and email in an 8-hour day and €65 per hour, that is 2.8 h a day, or €40,950 a year.

What share of deep work should I aim for?

The tool shows the result in green from 40% of the day, 3.2 h out of 8 h. This threshold is the tool’s own guide, not a standard.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.