HIIT timer — free interval timer with alarm

Set your work and rest seconds, pick the number of rounds, and Tickline handles the rest — beeping between phases, ringing at the end, and staying accurate even in a background tab. Try 40/20 for classic HIIT, 30/30 for beginners, or 50/10 for cardio finishers. Copy the URL to share the exact interval structure with a training partner.

Choosing your work and rest split

Beginners do best at 30/30 — equal work and rest keeps form intact. 40/20 is the classic conditioning ratio and the one most class formats use. 50/10 is a cardio finisher: short rest means the intensity has to be sustainable, so treat it as hard, not maximal. Tabata's 20/10 is a separate protocol with its own page.

How many rounds

Six to ten rounds is a complete session once you include a warm-up and cooldown. If the last round looks like the first, add rounds; if form breaks by round four, lengthen the rest before you shorten the session.

Using it in a gym

Turn on voice cues so you never look at the screen mid-effort, pick the beep alarm so round changes cut through music, and copy the link once you've dialled in a structure — the URL carries the work, rest and round counts, so a training partner gets the exact same session.