How to use it

Write one line under “What will you work on?” that you can check afterwards, such as “Draft the introduction and first two sections”. It is optional; the first press of Start nudges you once.
Pick a focus length (25, 50, 90, or 5 to 180 minutes) and a break length (5, 10, 15, or 1 to 60).
Press Start. The time left also shows in the browser tab’s title.
Pause for real interruptions. Stop early logs only the minutes you focused and marks the session as ended early.
When the sound plays, say what you got done and rate your focus (Scattered, Okay or Deep), then save.
Take the break. It starts automatically unless you turn that off.

Why write an intention first

Naming the work first borrows from research on implementation intentions, plans of the form “if X happens, I will do Y”, so the session starts with an action rather than a decision. Gollwitzer and Sheeran’s 2006 meta-analysis of 94 tests found a medium-to-large effect on goal attainment (d = 0.65). Those studies tested if-then plans, not a text field in a timer, so read this tool as an application of the idea, not a tested version of it. To move closer to the tested format, write “When the timer starts, I will open the draft and write the outline”; that adaptation is ours.

The closing questions record what happened rather than what you meant to happen, and give the block a clear end. We do not know that this helps you let go. The nearest evidence is Leroy’s 2009 pair of experiments, in which people who struggled to stop thinking about an unfinished task did worse on the next one. See our guides on attention residue and graduated friction.

How it works

The timer stores the moment the block should end and recalculates the time left from the clock about four times a second, so a busy page or a sleeping laptop cannot make it drift. Pausing stores what is left. The running session is saved in your browser, so a reload carries on; if the end passed while the page was closed, you see the finished session. The weekly chart uses your device’s calendar days and counts a session on the day it started.

What it does not do

It does not sync between devices or browsers, block websites or apps, ring when the page is closed, or send reminders. There is no account, and it cannot recover a log you clear or a browser profile you delete, so use Export CSV for a copy.

Choosing a session length

We found no study that identifies an ideal length. In Biwer and colleagues’ one-day study of 87 Dutch university students, those who chose their own breaks worked and rested longer and reported more fatigue and distraction and less concentration and motivation than students on 24/6 or 12/3 schedules; task completion did not differ. In Smits, Wenzel and de Bruin’s 2025 study, 94 students spent two hours on 25/5 Pomodoro, Flowtime or self-chosen breaks, and overall productivity, task completion and flow did not differ, although motivation fell faster under Pomodoro and Flowtime and fatigue rose faster under Pomodoro. A 2022 meta-analysis of breaks of ten minutes or less found small improvements in vigor and fatigue (d = 0.36 and 0.35) and no significant overall effect on performance (d = 0.16).

Our rule of thumb, not a result: 25 minutes to start avoided work, 50 for most focused work, 90 for work that takes time to load into your head. If “Scattered” clusters at the end of long sessions in your log, shorten them.

Using the log in a weekly review

Harkin and colleagues’ 2016 meta-analysis of 138 experiments (19,951 participants) found that interventions increasing progress monitoring modestly improved goal attainment (d = 0.40), more so when progress was physically recorded; the review is not specific to focus timers. Once a week, look at total minutes, sessions ended early, and intentions with no outcome, and carry one change into your weekly review.

Accuracy in background tabs

Browsers slow timers in hidden tabs. Chrome checks them at most once a second and, after five minutes hidden, can check long-chained timers only once a minute. Firefox for Android has a 15-minute minimum timeout for inactive tabs and may unload them. Because this timer works from a stored end time, the countdown is right the moment the page next draws. The end sound, the notification and the tab title depend on a timer firing, so they can be late. We schedule one timer for the exact end time, which Chrome’s documented rules treat more gently than a repeating one; still, treat the chime as a nudge, not a stopwatch.

Privacy

The timer’s own code makes no network requests, and your intentions, answers and log are never sent to us. They live in this browser’s local storage under keys starting “lhp.focusTimer”; Clear log or clearing site data removes them. The privacy policy covers the site-wide scripts this page also loads.

Frequently asked questions

Does the timer keep running if I close the tab?

When your browser allows storage, the timer saves the end time, so reopening shows the right time left or the finished session. It cannot ring while the page is closed, so keep the tab open if you want the sound.

Why was there no sound?

Browsers block audio until a page has seen a click or key press; Chrome documents that an audio context created before a gesture starts suspended. The timer starts its audio context when you press Start, and again at your next click or key press after a reload.

Why did no notification appear?

Notifications need your permission, requested only when you switch the option on. Nearly all mobile browsers refuse the kind a web page creates on its own, so on a phone rely on the sound and the on-page message.

How do I get my data out?

Export CSV downloads every session with ISO timestamps, minutes, your answers and the rating. Text starting with =, +, - or @ gets a leading apostrophe so spreadsheets do not run it as a formula; OWASP recommends this but notes it is unreliable in Excel once a file is re-saved.

Related guides

Make Your Phone Less Distracting Without Giving It Up: A 7-day phone reset built on what trials measured and what failed to replicate, with iPhone and Android settings checked against Apple and Google.
How to Time-Block a Deep-Work Day That Survives Meetings: Plan a deep-work day with block budgets, buffers tuned to your own log, a two-minute re-blocking routine for broken days, and templates for five roles.
Attention Residue: What Switching Tasks Costs and How to Cut It: What the research on attention residue shows, where the '23 minutes' figure really comes from, plus a one-minute resume note and a switch budget to try.
The 30-Minute Notification Audit for Mac, Chrome, and Your Phone: Audit notifications on Mac, Chrome, iPhone or Android, Slack and Teams in 30 minutes with one triage rule, exact settings paths and a 5-minute monthly re-check.

Sources

Gollwitzer & Sheeran (2006), Implementation intentions and goal achievement: A meta-analysis of effects and processes, Advances in Experimental Social Psychology.
Leroy (2009), Why is it so hard to do my work? The challenge of attention residue when switching between work tasks, Organizational Behavior and Human Decision Processes.
Biwer et al. (2023), Understanding effort regulation: Comparing “Pomodoro” breaks and self-regulated breaks, British Journal of Educational Psychology.
Smits, Wenzel & de Bruin (2025), Investigating the effectiveness of self-regulated, Pomodoro, and Flowtime break-taking techniques among students, Behavioral Sciences.
Albulescu et al. (2022), “Give me a break!” A systematic review and meta-analysis on the efficacy of micro-breaks for increasing well-being and performance, PLOS ONE.
Harkin et al. (2016), Does monitoring goal progress promote goal attainment? A meta-analysis of the experimental evidence, Psychological Bulletin.
Browser behaviour: Chrome timer throttling, Chrome autoplay policy, MDN setTimeout and Notification().
OWASP, CSV Injection.

Focus Session Timer

Your log