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30 Second Timer
Your half-minute countdown is ready: press Start (or Space) and the timer runs from 0:30 to zero with 3-2-1 warning beeps and an alarm. Perfect for planks, quick drills, tongue-twister challenges and game rounds.
0:30
Ready
Presets
Shortcuts: Space start / pause · R reset · F fullscreen. Add ?s=40 to the address to open a custom number of seconds.
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How to use the 30 Second Timer
- Press Start or hit the Space bar. The 0:30 countdown begins immediately.
- Leave the 3-2-1 beeps on to hear when the last seconds are ticking away.
- Fine-tune the length with the ± buttons or pick another preset.
- Choose an alarm sound and volume, then press Play test sound to check you can hear it.
- When time is up, press Stop alarm or Space. Press R to reset to 0:30.
How long is 30 second?
| Measure | 30 Second equals |
|---|---|
| Seconds | 30 s |
| Milliseconds | 30,000 ms |
| Hours | 0.008333 h |
| Share of a day | 0.0347% (1/2880 of a day) |
| Walking at 5 km/h (3.1 mph) | about 0.042 km (0.026 mi) |
| Speaking at 130 words per minute | about 65 words |
| Reading at 230 words per minute | about 115 words |
What you can do in 30 second
| Activity | Why 30 second works |
|---|---|
| Plank or wall sit | A classic beginner hold; repeat 3 to 5 times with rests |
| HIIT intervals | 30 s work and 30 s rest is one of the most popular interval patterns |
| Hand washing | The common 20 second guideline fits easily, with time to rinse |
| Elevator pitch | About 65 spoken words: just enough to say who you are and what you do |
| Game rounds | Charades, quick-draw and "name 5 things" rounds |
| Stretching | Holding a static stretch for about 30 seconds is a common recommendation |
How the countdown keeps exact time
When you press Start, the timer records the end moment as start time + 30,000 ms on the browser's monotonic clock (performance.now()). Every screen update subtracts the current time from that end moment instead of counting ticks, so a throttled background tab or a busy computer cannot make it fall behind. Pausing stores the time left, and Resume sets a new end moment that far in the future.
Frequently asked questions
How do I set a 30 second timer?
It is already set. Press Start or the Space bar and the countdown runs from 0:30 to 0:00, then the alarm rings until you stop it.
How many milliseconds are in 30 seconds?
30 seconds is 30,000 milliseconds, which is half a minute or about 0.00833 hours.
Can I hear a warning before the time is up?
Yes. With the "Beep at 3, 2, 1 seconds left" option switched on you hear short ticks in the final three seconds before the alarm.
Can I change the length?
Use the +5 s and −5 s buttons, pick a preset from 10 seconds to 2 minutes, or add ?s= and a number of seconds to the page address (for example ?s=40).
Does the timer keep running in a background tab?
Yes. It stores the exact end time and calculates the time left from the clock, so it stays accurate even when the browser slows down background tabs.
Is a 30 second plank good?
For many beginners a 30 second plank with good form is a solid start. Build up gradually with several rounds and rest in between. Stop if you feel pain.
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