A free interval timer
Set the work, set the rest, pick how many rounds. It counts you down out loud, keeps your screen awake, and stays out of the way. Nothing to install and nothing to sign up for.
Space bar starts and pauses. The screen stays awake while it runs.
What the numbers mean
Work is how long you go for. Rest is how long you get back. Rounds is how many times you repeat the pair.
The default here — 40 seconds on, 20 off, eight rounds — is the shape most circuit classes are built on. It is long enough that the last ten seconds cost you something, and short enough that you can hold decent form the whole way through. If you are new to this, start at 30 on and 30 off and earn the shorter rest.
Picking your own
Strength-biased work tends toward longer efforts and longer rests — 50 or 60 seconds on, 30 or more off — because the point is quality of movement rather than breathlessness.
Conditioning goes the other way: 20 to 40 seconds on with short rest, so the effort accumulates and your heart rate never fully comes back down.
There is no magic ratio. The honest rule is that the interval should be hard enough that you want it to end, and the rest short enough that you do not fully recover.
The screen stays on
The timer holds a wake lock while it is running, so your phone will not go dark between rounds. It also beeps down the last three seconds of every interval, so you can put the phone on the floor and stop looking at it.
Questions
Is this interval timer free?
Yes, completely, and there is nothing to sign up for. It runs in your browser and does not ask for an account. The full STATIONS workout builder is free too — the only paid part is training with a friend over live video.
Do I need to install anything?
No. It is a web page. If you want it to behave like an app, add it to your home screen from your browser's share menu and it will open full-screen without the browser chrome.
Will it keep running if I lock my phone?
The timer requests a wake lock so the screen stays on while it runs, which is the reliable path. If you lock the phone anyway, browsers may suspend the page and the countdown beeps can stop. Leave the screen on.
What is a good work-to-rest ratio?
For general conditioning, a 2:1 ratio like 40 seconds on and 20 off is a sensible default. For heavier or more technical work, move toward 1:1 or even 1:2 so you can keep your form. Adjust based on whether your last round looks like your first.
Can it build the whole workout for me?
That is what the main app does. STATIONS generates a 45-minute circuit — nine stations a half, two halves — with an animated demonstration of every exercise and your own music running with the clock.
STATIONS turns these intervals into a full 45-minute session — nine stations a half, two halves, an animated demonstration of every exercise, and your own SoundCloud or Mixcloud mix running with the clock. You can also start a video call and train with a friend on the other end. Free, no account.
Build a session