Forty-five minutes is the length of a school lesson and a strong deep-work block — long enough for real depth before attention naturally fades. This free 45-minute timer runs full-screen in your browser with an alarm and stays accurate in background tabs.
What is a 45 minute timer good for?
- A class period, lecture or tutoring session
- A deep-work or revision block before a break
- A full gym session or long workout
- A long-form reading or writing sprint
How this 45 minute timer works
Press Start and the countdown runs full-screen in your browser; press it again to pause and resume, hit Reset to return to 45 minute, or +1 min to extend. You can also press the spacebar to start or pause. It is wall-clock accurate, so it stays correct even in a background tab, and it rings when it reaches zero. Need a different length or a stopwatch and date countdown? Open the full timer.
Frequently asked questions
Why time a 45-minute block?
Forty-five minutes maps onto how many schools and universities structure a lesson, and it is close to the upper limit of sustained focus for most people before a break sharply improves the quality of the next block. Timing it matters because deep work needs a defined boundary: knowing the session ends at the alarm lets you commit fully without checking the clock, and the hard stop protects the break that keeps the next 45 minutes productive. Start it, remove distractions, and work until it rings.
Does the timer keep accurate time if I switch tabs?
Yes — the 45 minute timer stays wall-clock accurate in a background tab. Instead of counting ticks (which browsers throttle in background tabs), it records the exact end time and works out the remaining time from your clock on every update, so the figure on screen is always correct. When you return to the tab the display instantly shows the true time left. The alarm tone is generated with the Web Audio API and plays when the countdown reaches zero with the page on screen, so keep the tab visible if you need the sound at the exact second.
Will it make a sound when it finishes? Is it free?
Yes to both — the 45 minute timer rings at zero and is completely free. When the countdown reaches zero it plays three short rising tones and the card flashes with a “Time’s up” message, so you are notified even with the sound off — use the speaker button to mute or unmute. The first time you press Start the browser unlocks audio from that tap, which is why a timer you start yourself can ring later. It runs entirely in your browser, needs no sign-up, and nothing is uploaded.
How does the 45 minute timer display the time remaining?
The 45 minute timer shows minutes and seconds, starting at 45:00 and counting down to 00:00, with an hours field appearing only on countdowns longer than an hour. Seconds are rounded up, so the display reads 45:00 for the first moment after you press Start rather than jumping straight to 44:59. The digits are redrawn continuously while the arc around them drains in proportion to the time left. At zero the card flashes and shows the “Time’s up” message.