Free tool
Real Focus Time Timer
Most timers count down wall-clock minutes, which quietly credit you for time you spent handling a Slack ping or a knock on the door. This one tracks the two numbers separately — planned duration vs. minutes you were actually, unbrokenly focused — so a 45-minute block with three interruptions shows you the real cost instead of hiding it.
You just watched the gap between wall-clock time and real focus open up by hand, and had to do the mental subtraction yourself. Groundkeep’s built-in focus session timer does this against a real task on your board: it logs actual worked seconds per session, and when you’re done that number rolls straight into the task’s real actual-time-spent (not the estimate you guessed at) — building an estimation-accuracy history across every task like this one, automatically, with nothing to copy into a spreadsheet.