You've just finished a grueling three-mile run, or at least you think it was three miles. You glance down at your wrist, sweaty and out of breath, only to see "5.01 KM" staring back at you. It’s annoying. Most of us in the States or the UK think in miles for distance, but sometimes the Apple Watch—for reasons known only to its internal logic—decides you're a metric athlete today.
Basically, it’s a settings mismatch.
If you're wondering how to change kilometers to miles on Apple Watch, you've likely dug through the "Workout" app on the watch itself and found nothing. That's because Apple buries these settings in a couple of different places depending on whether you want to change the units for a specific run or for your entire health profile. It’s not just one "magic button" you toggle. It's actually a bit of a dance between your iPhone and the watch on your wrist.
The Quick Fix Within the Workout App
Sometimes you don't want to change your whole life; you just want this specific run to show miles. If you’re already in the Workout app, there’s a way to do this, but it’s hidden behind the three little dots (the ellipsis) on the workout card.
Open the Workout app on your Apple Watch. Before you tap "Outdoor Run" or "Outdoor Cycle," tap those three dots in the top right corner. You'll see a list of goals like Calories, Distance, and Time. Tap "Distance." Once you're in there, firmly press the screen—or scroll down depending on your watchOS version—and you should see the option to swap between KM and Miles.
It's weirdly tactile.
Apple’s Force Touch used to handle this, but now it’s mostly about scrolling and tapping the right sub-menu. If you change it here, the watch usually remembers it for next time. Usually. But if your watch keeps reverting back to kilometers like it's trying to force you to learn the metric system, you have to go deeper into the Health settings on your iPhone.
Fixing the Global Settings via iPhone
Most people don't realize that the Apple Watch is basically a mirror of your iPhone's Health profile. If your "Health Details" say you're a metric person, the watch will obey that.
- Grab your iPhone.
- Open the Health app.
- Tap your profile picture or the little icon in the top right.
- Hit Health Details.
Look at your height and weight. If these are set to centimeters and kilograms, your watch might default to kilometers for distance. But the real kicker is under "Units." You need to go back to the main "Summary" or "Browse" tab, search for "Walking + Running Distance," and scroll all the way to the bottom. There’s a "Unit" section there. Tap it. Select "mi" instead of "km."
Changing it here is like changing the DNA of your tracking. It forces the Watch to sync up.
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Honestly, it’s a bit of a mess that these settings are scattered. You’d think a "Units" toggle would be front and center in the Watch app, but Apple prefers to tie everything to your medical profile.
Why Did My Apple Watch Change to Kilometers Anyway?
It happens.
Software updates are usually the culprit. When watchOS 10 or 11 rolls out, sometimes the default regional settings get a little jittery. Or, if you’ve traveled recently, the watch might have tried to be "helpful" by switching to the local standard. It's the tech equivalent of a "when in Rome" attitude that nobody actually asked for.
Another weird quirk? The "Region" setting in your General settings. If your region is set to "United Kingdom" or "Canada," the watch might default to metric for certain activities even if you’ve set other things to Imperial. Go to the Watch app on your iPhone, tap General, then Language & Region. Make sure your "Measurement System" is set to "US" or "Imperial" if you want miles.
The Nuance of "Automatic" Settings
Apple loves the word "Automatic."
In the Language & Region settings, there is a toggle for "Automatic." This pulls data from your GPS location to decide what units to use. If you live near a border or you’re using a VPN that pings a server in Europe, your watch might get confused. Turning off "Automatic" and manually selecting your preferred measurement system is the only way to stay sane if you're a frequent traveler.
It’s worth noting that changing these units won’t erase your old data. If you ran 5km yesterday and you change your watch to miles today, that 5km entry stays in your history as 3.1 miles. The math happens in the background. Your Apple Watch is essentially a high-powered calculator strapped to your arm; it doesn't care about the unit, only the raw GPS pings.
Dealing with Third-Party Apps
If you use Strava, Nike Run Club, or Peloton, changing the units on your Apple Watch might not do a damn thing.
These apps often have their own internal settings that override the Apple Health defaults. If your Apple Workout app shows miles but your Strava app shows kilometers, you have to go into the Strava app settings on your phone—not the watch—to fix it. In Strava, for example, it’s under Settings > Units of Measure.
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Don't go crazy trying to find a "global" switch that fixes every app at once. It doesn't exist. Each app developer has to choose to respect Apple's system settings, and many of them... well, they just don't.
Actionable Steps to Standardize Your Units
To make sure you never have to deal with the KM vs. Miles headache again, follow this specific order of operations. It covers all the bases where the setting might be hiding.
- Check the Watch App on iPhone: Go to My Watch > General > Language & Region. Set the "Measurement System" to "Imperial." This is the "big" switch.
- Update the Health App: Open Health > Browse > Activity > Walking + Running Distance. Scroll to "Unit" and pick Miles.
- Force a Sync: Sometimes settings don't take immediately. Toggle Airplane Mode on and off on your watch to force it to re-sync its data with your iPhone.
- The Workout Ellipsis: Next time you start a run, check the three dots. If it says "KM," tap it and change the goal to "Miles" right then and there.
By hitting all three of these spots, you're essentially cornering the software and forcing it to comply. It's an annoying quirk of an otherwise very polished device, but once it's set, it usually stays put until the next major OS overhaul.
Now, go get those miles. Or kilometers. Whatever makes you move.