Interval timer
Work, rest, rounds and sets, with a 3-2-1 count into every change and a distinct tone for work and rest so you can train without looking.
Total 9:40 · work 5:00 (52%) · 20 segments. Three short beeps count you into every change; a finish chime marks the end.
Describe a workout, get a timer
Write it the way your coach or app wrote it. The planner turns it into timed segments you can check before loading.
Uses an AI model through Vercel AI Gateway, only when you press the button. Your text is sent to generate the plan and isn’t stored by CountdownPro. Check the plan before you start; it’s timing help, not training advice.
Alarm & notification settings
Sound needs one tap on the page first (a browser rule). Keep this tab open: closing it stops every timer’s alarm. Why timers stay accurate in background tabs.
Work-to-rest ratios, explained
The ratio of work to rest decides what an interval session trains. Shorter rest than work (2:1, like 40/20) keeps your heart rate high and trains you to recover under fatigue. Equal work and rest (1:1, like 30/30) lets you keep quality up across more rounds. Longer rest than work (1:2 or 1:3) is used for all-out sprints, where you need nearly full recovery to repeat the effort.
| Style | Typical work / rest | Used for |
|---|---|---|
| Tabata | 20 s / 10 s × 8 | Four minutes of very hard effort |
| HIIT | 30–45 s / 15–30 s | General conditioning circuits |
| EMOM | Every 60 s | Strength and skill work at a steady pace |
| Boxing rounds | 3 min / 1 min | Bag, pad and sparring rounds |
| Run-walk | 1 min / 1–2 min | Building up to continuous running |
The coloured strip under the dial is your whole session drawn to scale: tangerine for work, green for rest, yellow for getting ready. Change any number and it redraws, along with the total time and the share of it you spend working.
Questions
How do I set up an interval timer?
Enter your work time, rest time and number of rounds. Add sets if you repeat the block, with a longer break between sets, plus an optional warm-up (“get ready”) and cool down. Press Start and the timer beeps three times before every change.
What is a good interval for beginners?
Many beginner plans start with more rest than work, such as 20 seconds of work and 40 seconds of rest for 8–10 rounds, then shift the ratio as fitness improves. If you have a health condition, check with a professional before starting high-intensity training.
Can I use it for running intervals?
Yes. Set work to your run or sprint and rest to your walk or jog recovery, e.g. 60 seconds run and 90 seconds walk for 8 rounds. Turn on notifications and the sound so you hear the change with the phone in your pocket, and keep the screen awake.
Does it keep time with the screen off?
Keep the tab open. The timer can keep your screen awake while it runs. If your phone locks anyway, the position is recalculated from the start time when you come back, so you land on the right round. Sounds scheduled on the audio clock usually still play while locked on Android; iOS may pause them.
What does the “describe a workout” box do?
You type your workout in plain words and an AI model turns it into a list of named segments with times. You see the list before loading it, and the timer runs it like any other plan.