Checking a week of training can turn into another task: open each workout, inspect the charts, then try to hold the whole week in your head. Even a simple question such as how much of it was easy depends on whether you count sessions or minutes.
Zonometry makes that check quick and visual. The free iPhone app turns Apple Health data into a colourful running track showing easy, moderate and hard effort. Developer Philip Seifi built it to make training balance enjoyable to look at, even with only a moment to spare.
How it works
TL;DR: Zonometry reads the workouts and heart-rate readings already in Apple Health, then shows the training mix on a track. Heart-rate time and whole-session effort are separate views. There is no extra workout logging and no app account.
The track covers a day, a week, a month or six months. Local weather can bring sunlight, clouds, rain or night lighting to the scene. The app also lets you:
- Review the overall balance before opening individual workouts.
- Explore recorded running routes, heart-rate zones and other workout details.
- Adjust heart-rate boundaries and training targets to suit your own setup.
Why sessions and minutes tell different stories
A hard interval session can contain plenty of easy warm-up and recovery minutes. An easy-rated session can also include minutes above the easy heart-rate boundary. A count of sessions and a count of heart-rate minutes answer different questions.
Take an illustrative month, not a real athlete’s. Sixteen of 20 rated sessions are easy, but only 600 of 1,000 counted heart-rate minutes are. That is 80% easy sessions and 60% easy minutes.
| View | Easy | Total counted | Easy share |
|---|---|---|---|
| Session effort | 16 sessions | 20 sessions | 80% |
| Heart-rate time | 600 minutes | 1,000 minutes | 60% |
A gap like that is a reason to look at the workouts and the zone settings. On its own, it does not show that a runner trained incorrectly. Zonometry keeps the counting method visible so the comparison has a clear meaning. Its developer explains the two methods in more detail in a guide to sessions versus minutes.
The data behind the track
Apple Health is the only data source. The balance uses workout records, heart-rate readings and, for the session view, effort ratings. Extra running details depend on the route and metrics saved with each workout, and cardio fitness comes from the VO2 max readings stored in Apple Health.
An Apple Watch supplies workouts and heart rate to Apple Health directly. Other devices depend on what their companion apps actually write there, and a workout summary without a usable heart-rate stream is not enough to work out time in zones.
Zonometry does not connect directly to Garmin, COROS, Polar or Strava accounts. Imports from those services through Apple Health have not been tested end to end for this article.
Choosing the boundaries
Heart-rate boundaries are adjustable. On iOS 27, where Apple Health’s heart rate zones are available, Zonometry groups Apple’s zones 1 and 2 as easy, zone 3 as moderate, and zones 4 and 5 as hard. On older systems, or when those zones are unavailable, you set the boundaries in the app.
The starting custom boundaries are 140 and 165 bpm. They are editable starting values, not measurements of any runner’s thresholds. Whole-session effort uses a different scale:
- Easy: an effort rating below 4.
- Moderate: from 4 to below 7.
- Hard: from 7 to 10.
Unrated sessions do not count as easy by default.
Price and first use
Zonometry is free for iPhone on iOS 17 or later, with no subscription, in-app purchases or account. An example week is available before you grant Apple Health access, and the app then needs permission to read the relevant records. Health data is processed on the phone. Optional weather uses a chosen city or your approximate location.
Quick answers
Where do Zonometry's heart-rate boundaries come from?
On iOS 27, Zonometry can use the heart rate zones in Apple Health. Otherwise you set them in the app, starting from 140 and 165 bpm. The boundaries describe your chosen setup and are not a lab measurement.
Will Garmin, COROS or Polar workouts count in Zonometry?
Only if the workouts and their heart-rate readings reach Apple Health in a usable form. The workout record and the heart-rate stream are separate requirements, and those import paths have not been tested end to end.
Do I need to record workouts again for Zonometry?
No. Zonometry reads your existing Apple Health records. The session view needs effort ratings and the heart-rate view needs heart-rate readings.
More information: zonometry.com and the App Store.
Author: Philip Seifi, developer of Zonometry, edited by the5krunner.
If you enjoyed reading this, here is another in the Indie Spotlight series: Indie App Spotlight: Pyre Fitness puts a fantasy hunter on your run.
Last Updated on 23 October 2026 by tfk the5krunner
Small things I always use
- Garmin 90-degree charging adapter: Charges your Garmin from any USB-C cable. Essential when travelling. I use one.
- Body Glide: The blue anti-chafe stick swimmers and runners carry. I use it.
- Speedo earplugs: Fewer ear infections and no cold-water dizziness. I use them.
- Dryrobe Advance: My winter changing robe for open-water swims. I use one. A cheaper option is the AONYIYI changing robe.
- Maurten: Race fuel that stays easy on the stomach. I use them.
- Beet It Sport nitrate shots: Beetroot shots I take in the days before a race. I use them.
- Garmin charging puck: The quickest way to top up before a session. I use one.
- Injinji: Toe socks that stop rubbing, so you run more. I use them.
- Ultimate toe protectors: Stop black toenails on long runs. They work. I use them.
- Compressport R2 v2 calf sleeves: My calf sleeves of choice. I use them.
- Cellucor C4: My pre-workout before hard sessions.
- TPU tubes: Schwalbe Aerothan, Tubolito and Pirelli SmarTube. Light, tiny spares. I use all three.
- G8 insoles: Adjustable insoles that are good. I use them.
- Cycplus Cube: A 97g electric pump that gets a road tyre rideable in two minutes. I carry one. 5% off with code THE5KRUNNER.
Watches and sensors
- Polar H10: My daily driver for waking HRV.
- Polar Verity Sense: My backup arm-worn HR sensor.
- Nomad bedside charger: Charges my iPhone and Apple Watch overnight. I use it, and many of their bands.
- Train.Red: The best muscle oxygen sensor I’ve used.
- Tymewear: Accurate heart rate and reliable ventilatory zones. I use it to pace endurance rides over an hour.
- Garmin Forerunner 970: A pro-grade triathlon watch. I use this.
- Apple Watch Ultra 4: My daily smartwatch. No phone needed on rides.
- Garmin Fenix 9 Pro: I’ve just bought one.
On the bike
- Continental GP5000 for everyday riding, and Aero 111 on the front for special occasions.
- Helmets: Specialized S-Works Evade 3 for road riding, and Rudy Project Wing for TT-style races. I use both.
- Ravemen FR300: A front light that mounts under your Garmin or Wahoo. I use one.
- Wahoo TRACKR Radar: I use it on one bike and Varia on the other. They perform the same.
- Garmin Varia RTL515: Radar that warns you of cars from behind. I use this model.
- Wahoo ELEMNT Roam 3: The bike computer that’s easy to use. I use mine on most rides.
- Favero Assioma Pro RS2: Accurate power pedals that swap easily between bikes. I use this model.
Home and indoor training
- NPE Runn: Makes my basic treadmill smart, sending more accurate speed and distance to my watch and Zwift. I use it.
- Google Wifi: Keeps Zwift connected in my pain cave. I use it.
- Apple TV 4K: Zwift on the big screen. I use two.
- Google Nest Doorbell (wired, 2nd gen): My video doorbell, running in both Google Home and Apple Home. I use it.
Health, recovery and sleep
- FreeStyle Libre 3 Plus: Shows how my blood sugar responds to diet.
- hDrop: Measures my sweat loss in summer and indoors.
- Fourth Frontier Zone: Checks my heart under load in hard sessions.
- Oura Ring 5: My partner’s recovery tracker of choice.
- Eight Sleep: A cooling mattress cover my partner and I use nightly.
Reader-Powered Content
This content is not sponsored. It’s mostly me behind the labour of love, which is this site, and I appreciate everyone who supports it.
Support the site: Follow (free, fewer ads) · Subscribe (paid, ad-free) · Buy Me A Coffee
Written by real people, with AI assistance. Fact-checked and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.
tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. See the gear tfk uses. ID
