Your training zones, in light.

Zonal turns your Philips Hue lights into a live heart-rate zone display. Glance at the room, not your phone, to know how hard you're working.

Coming soon to the App StoreFree · iPhone · iOS 26

Zonal's session screen: ZONE 4, Threshold, 154 bpm, Heart rate · Lights synced, with Zone 4 lit on the five-zone strip, 15 seconds elapsed, and a Stop button.

Five heart-rate zones, one colour each

Zones come from your max heart rate, or from your threshold heart rate if you know it. The colours are tuned from the zone colours Zwift riders already know, so the room reads at a glance.

  1. Zone 1 · Recovery

    Easy effort: warm-ups, cool-downs and recovery days.

    Heart rate
    Under 60% of maxUnder 68% of threshold
    Room
    Blue, low
  2. Zone 2 · Endurance

    Long, steady work. Zone 2 training by the room: hold the green for an hour without looking down.

    Heart rate
    60–70% of max68–84% of threshold
    Room
    Green, medium
  3. Zone 3 · Tempo

    Comfortably hard. On an easy day, gold means you've drifted up out of Zone 2.

    Heart rate
    70–80% of max84–95% of threshold
    Room
    Gold, medium-high
  4. Zone 4 · Threshold

    Hard, sustained efforts around your threshold.

    Heart rate
    80–90% of max95–106% of threshold
    Room
    Orange, full
  5. Zone 5 · VO2 Max

    Short, all-out intervals.

    Heart rate
    90% of max and up106% of threshold and up
    Room
    Red, full

Room brightness never goes above the Max brightness you choose: 25, 50, 75 or 100%.

Sync your Hue lights to your heart-rate zone

  1. Put on your heart-rate monitor

    Any chest strap or armband that broadcasts standard Bluetooth heart rate, from Polar, Wahoo, Garmin and others. Zonal reconnects it each time you open the app.

  2. Tap Start

    The room eases to a soft white, then to your zone's colour once your heart rate settles. Opening the app never touches your lights. Only Start does.

  3. Train, then tap Stop

    Lock your phone if you like: your zone stays on the lock screen and in the Dynamic Island. Stop puts every light back exactly how it was. Nothing is recorded.

Setup happens once: pair your Hue Bridge, choose the lights around your bike or treadmill, pair your monitor and set your max heart rate.

Zonal's Home screen: Ready to train, the five zones numbered 1 to 5, a heart-rate monitor connected at 147 bpm, 6 lights ready, and a Start button.

The room moves when your effort does

Lights that change on every heartbeat are a distraction. Zonal smooths your heart rate and waits for a new zone to hold before the room follows. Every change is a slow fade. Nothing flashes.

Averaged over5s
Your heart rate is averaged over five seconds. That's the number on screen, too.
To step up8s
A higher zone has to hold for eight seconds before the room steps up.
To step down20s
A lower zone has to hold for twenty, so a short easy stretch doesn't drop the room.

Before you train, Your zones lists your bpm range for each zone and can hold any of them on your lights, so you know what Zone 2 looks like in your room.

The Your zones sheet, from a max heart rate of 185 bpm: Zone 1 Recovery under 111 bpm, Zone 2 Endurance 111–129, Zone 3 Tempo 130–147, Zone 4 Threshold 148–166 and Zone 5 VO2 Max 167 and up, each with a Show button to test it on the lights.

Works alongside your training app

Zonal doesn't replace your training app. Keep riding Zwift, Rouvy, Peloton or TrainerRoad, run on a treadmill, row, or spin with no app at all. Zonal only listens to your heart-rate monitor and never controls your trainer.

Questions

What do I need?

An iPhone on iOS 26 or later, a Bluetooth heart-rate monitor, and for the room, a Philips Hue Bridge on the same Wi-Fi with colour-capable Hue lights. Lights are optional: without them, Zonal shows your zone on screen.

Will my lights go back to normal?

Yes. Zonal saves each light's state when you tap Start, and Stop puts every light back exactly how it was. If Zonal is closed before you tap Stop, it offers to restore your lights the next time you open it.

Does Zonal store my heart rate?

No. Your heart rate is read live to set your lights. It's never stored and never leaves your phone. There's no account and no workout history. See the privacy policy.

How much does it cost?

Zonal is free.

Coming soon to the App Store

Questions before then? Write to support@zonal.fit.