20 Minute Timer
Free online 20 minute timer with alarm. Starts the second the page loads, keeps true time even when throttled, rings until dismissed. Free, no sign-up.
Click anywhere on the page to enable the alarm sound
Quick Answer
This free online 20 minute timer counts down from 20 minutes with a repeating alarm and starts the moment the page opens. Timing uses your device's real clock, so the countdown stays exact even in a background tab. Twenty minutes is the NASA-recommended power-nap length Pause, resume, or extend any time — free, no sign-up.
How It Works
Open the page — the countdown from 20:00 starts automatically
Click anywhere once to unlock the alarm sound (browser autoplay rules)
Pause, resume, or reset at any time — the remaining time is stored exactly
When the alarm rings, press Dismiss to stop the chime, or +1 min to extend
Key Facts
- Counts down from 20:00 automatically — no start button needed
- Alarm is a repeating two-tone chime that rings until you press Dismiss
- Timestamp-based math keeps the countdown exact across tab switches and throttling
- Pause/resume stores the precise remaining time — no drift after pausing
- +1 minute button extends the countdown instantly, even while the alarm rings
- Browser tab title shows the live countdown, e.g. "9:58 - Timer"
- Click anywhere once to enable sound (browser autoplay rules)
- 100% client-side and free — nothing is uploaded or tracked
Frequently Asked Questions
How do I set a timer for 20 minutes?
Just open this page — the 20 minute timer starts counting down immediately, no configuration needed. If you've paused or reset it, press Resume or Reset to begin the full 20-minute countdown again.
Will the alarm ring if I switch tabs?
Yes. The countdown is computed from real clock timestamps rather than counted ticks, so browser tab throttling cannot make it inaccurate — the digits snap to the true remaining time when you return. The alarm sound will play as long as you have clicked anywhere on the page at least once, because browsers require one user interaction before allowing audio.
Can I pause the timer and resume later?
Yes. Pause freezes the exact remaining milliseconds; Resume recalculates the end time from that remainder, so nothing is lost or drifted. You can also press +1 min at any point to extend the countdown, or Reset to start the full duration over.
What is a 20-minute timer used for?
Twenty minutes is the NASA-recommended power-nap length — long enough to restore alertness, short enough to avoid sleep inertia — and a standard HIIT or yoga block.
Is this timer free?
Completely free with no sign-up, no ads on the timer itself, and no limits. Everything runs locally in your browser — the countdown and alarm keep working even after you go offline.
Why set a timer for 20 minutes?
Twenty minutes is the NASA-recommended power-nap length — long enough to restore alertness, short enough to avoid sleep inertia — and a standard HIIT or yoga block.
NASA found a 26-minute pilot nap improved performance by 34%; a 20-minute timer keeps you inside the light-sleep zone so you wake up clear.