# Five watch zones. One clearer picture. Apple Watch gives you five heart-rate zones. Here’s how Zonometry groups them into three, and how to choose boundaries that fit you. Author: Zonometry Reviewed: 2026-09-21 Canonical: https://zonometry.com/guides/apple-watch-heart-rate-zones/ ## Contents - How does Zonometry group Apple Watch zones?: https://zonometry.com/guides/apple-watch-heart-rate-zones/#mapping - What does Apple estimate?: https://zonometry.com/guides/apple-watch-heart-rate-zones/#apple-estimates - A worked example in beats per minute: https://zonometry.com/guides/apple-watch-heart-rate-zones/#worked-example - When to use custom boundaries: https://zonometry.com/guides/apple-watch-heart-rate-zones/#custom-boundaries - Why doesn’t zone time always equal workout time?: https://zonometry.com/guides/apple-watch-heart-rate-zones/#coverage - How to compare the app with Fitness: https://zonometry.com/guides/apple-watch-heart-rate-zones/#compare - Sources: https://zonometry.com/guides/apple-watch-heart-rate-zones/#sources ## How does Zonometry group Apple Watch zones? Zonometry turns Apple Watch’s five zones into three clear bands: easy, moderate and hard. Zones 1 and 2 become easy, zone 3 becomes moderate, and zones 4 and 5 become hard. Open the app after a run to see how your effort adds up. Apple Watch → Zonometry Zones 1 + 2→1 · Easy Zone 3→2 · Moderate Zones 4 + 5→3 · Hard Readings below your minimum counted heart rate are excluded. Apple’s estimated boundaries may differ from your measured thresholds. If you know your LT1 and LT2 heart rates, you can use custom boundaries instead. ## What does Apple estimate? Apple describes its heart-rate zones as estimates based on health data. You can also configure the boundaries manually in the Watch app or on Apple Watch. That means “Apple zones” can refer to automatically calculated values or values someone has entered themselves; check the settings rather than assuming everyone uses the same numbers. [1] (https://zonometry.com/guides/apple-watch-heart-rate-zones/#source-1) Seiler’s three-zone model uses two measured thresholds to separate easy, moderate and hard exercise. Your watch estimates its boundaries from health data, so an individual exercise test can help you personalize them. [2] (https://zonometry.com/guides/apple-watch-heart-rate-zones/#source-2) If you have changed your watch zones manually, check where those values came from and when they were last updated. ## A worked example in beats per minute Suppose a watch has zone 3 beginning at 139 bpm and zone 4 beginning at 151 bpm. With a minimum counted heart rate of 101 bpm, Zonometry’s grouping would look like this: Example heart-rate ranges | Band | Range | What goes here? | Easy | 101–138 bpm | Eligible time in Apple zones 1 and 2 | Moderate | 139–150 bpm | Apple zone 3 | Hard | 151 bpm and above | Apple zones 4 and 5 | Excluded | Below 101 bpm | Below this example’s counting minimum A reading of 150 bpm belongs in moderate; a reading of 151 bpm belongs in hard. If the hard boundary were instead placed at the start of Apple zone 5, the whole of Apple zone 4 would fall into the middle band. That would be a different grouping and would change the displayed mix without changing the underlying workout. To check your own ranges, look at where Apple zones 3 and 4 begin. Those are the two numbers Zonometry uses to separate the three bands. ## When to use custom boundaries If you have individual threshold information, you can use it to choose your boundaries instead of relying on the automatic grouping. In Zonometry’s training settings, inspect the displayed ranges and use the zone-adjustment controls to enter personal values. The first boundary must be below the second; the minimum counted heart rate must be below the first. Record the context alongside your own training notes: the date of the assessment, the exercise mode, and how the thresholds were identified. That makes a future comparison more useful than simply remembering two numbers. The research literature uses several methods to quantify intensity, which is one reason apparently similar zone distributions are not always directly comparable. [2] (https://zonometry.com/guides/apple-watch-heart-rate-zones/#source-2) A small boundary change can move several minutes between colours. If you lower the hard boundary from 155 to 151 bpm, for example, time at 152 bpm moves from moderate to hard. Keep the same settings when you want to compare weeks. ## Why doesn’t zone time always equal workout time? Zonometry counts time from each heart-rate reading to the next, up to 30 seconds or the end of the workout. It leaves out pauses and readings below your minimum heart rate. The “covered” time tells you how much of your workout contributes to the chart. A 40-minute run might have 37 counted minutes after pauses, gaps and low readings are removed. Your percentages are calculated from those 37 minutes. Example · 40-minute workout 206113 20 min easy6 min moderate11 min hard3 min not counted Of the 37 counted minutes, about 54% are easy, 16% moderate, and 30% hard. Grey shows the three minutes left out. Zonometry filters out very low heart-rate readings so your training mix focuses on time spent exercising. It sets the minimum automatically, and you can adjust it in Settings. The automatic value is 55% of your maximum heart rate, rounded to a whole beat and kept below the moderate zone. ## How to compare the app with Fitness - Open the same workout. Make sure the dates, start time, and activity match. - Compare actual boundaries. Check the start of Apple zones 3 and 4 against the moderate and hard boundaries shown in Zonometry. - Account for the minimum and coverage. Check the covered time shown above your zone totals. - Group before comparing. Add Apple zones 1+2 and 4+5 rather than comparing two rows both called “zone 2.” - Expect estimates to differ slightly. The apps can count gaps, pauses and rounded readings differently. If the ranges are right but the weekly mix still feels surprising, the next question is usually how you are counting and which period you are looking at. Continue with the training-distribution guide (https://zonometry.com/guides/training-distribution/) for examples of hard sessions, easy recoveries, and incomplete weeks. ## Sources - Apple. View Heart Rate Zones on Apple Watch. (https://support.apple.com/guide/watch/view-heart-rate-zones-apd897dccddf/watchos) Official guide to estimated and manually configured zones. - Stöggl TL, Sperlich B (2015). The training intensity distribution among well-trained and elite endurance athletes. (https://doi.org/10.3389/fphys.2015.00295) Definitions and measurement issues. Read our paper notes. (https://zonometry.com/science/training-intensity-review-2015/)