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The quick answer
Best for most slim wrists
Opens Amazon.com · Prices change often
Garmin Forerunner 70Best small Garmin for a first training planUnder $250
Garmin Forerunner 170 MusicBest small watch for phone-free SpotifyUnder $350
Amazfit T-Rex 3 ProBest small case with maps that reroute youUnder $400Price bands, not prices
| Watch | Verdict | Who it suits | The catch | Price band and link |
|---|---|---|---|---|
 COROS PACE 4Our pick | Best for most slim wrists | Runners with small wrists who want multi-band GPS, maps and long race battery in the lightest case | Wrist heart rate splits testers in cold weather and on sharp pace changes | Under $250View on Amazon (opens in a new tab) |
| Garmin Forerunner 70Buy | Best small Garmin for a first training plan | Newer runners with slim wrists who want Garmin Coach plans and Garmin's app | Leaves out multi-band GPS, music, payments and a barometer | Under $250View on Amazon (opens in a new tab) |
| Garmin Forerunner 170 MusicBuy | Best small watch for phone-free Spotify | Slim-wrist runners whose music lives in Spotify, Amazon Music, Deezer or YouTube Music | Garmin rates it at 7.5 hours of GPS with music playing | Under $350View on Amazon (opens in a new tab) |
| Amazfit T-Rex 3 ProBuy | Best small case with maps that reroute you | Trail runners and hikers with smaller wrists who want maps, a flashlight and sapphire | The smaller case gives up about a third of the larger model's accurate-GPS hours, and nobody has measured its battery | Under $400View on Amazon (opens in a new tab) |
 Garmin Forerunner 970Buy | Best if you'll wear 47 mm for maps and a flashlight | Runners with slim but not tiny wrists who want Garmin's full kit and its best wrist heart rate | One size only, and the heaviest of the picks | Under $800View on Amazon (opens in a new tab) |
Watch makers have a generous idea of what fits a small wrist. Garmin lists its 51 mm Enduro 4 for wrists very nearly as small as the slim vívoactive 6, which is a statement about the strap, not the case. So we read the case, the thickness and the weight instead, part number by part number, against what testers put on a scale. Milewright's pick for a slim wrist is the COROS PACE 4. COROS's spec sheet gives it 1.1 oz (32 g) on the woven strap, and a case just 0.46 in (11.8 mm) thick.
Yet it keeps what smaller watches usually drop: multi-band GPS, topo maps since the September firmware, and more race battery on the box than any other small watch here. The catch is wrist heart rate. Testers mostly saw it keep step with a strap. But one careful winter test and a handful of owners caught it locking onto cadence in the cold. If you train strictly by heart rate through a northern winter, budget for a strap.
COROS PACE 4Under $250Opens Amazon.com · Prices change often
Weight and thickness matter more than the number on the box. A light, thin watch stays where you put it. Staying put is the whole job of the sensor on the back. Heavy watches on slim wrists show the opposite. The steel Suunto Vertical 2 slid toward one tester's wrist bone and read poorly until it was moved up the arm. The tester of the 51 mm Enduro 4 blamed the case for a long run where wrist heart rate missed whole stretches. Garmin's own heart rate guidance says the same in drier words: snug, above the wrist bone, on a silicone strap.
Then decide what you refuse to give up. The small Garmins drop multi-band GPS. Garmin's watch with everything comes only at 47 mm. If phone-free Spotify matters more than maps, the answer moves to the Forerunner 170 Music. If you'll take a 47 mm case for Garmin's maps and flashlight, it moves to the Forerunner 970. For everyone else, it stays with the PACE 4.
Price band: under $250
The box says 31 hours of dual-frequency GPS, in a case 1.71 in (43.4 mm) across. With the screen always on, COROS's battery page gives the PACE 4 24 hours in that mode. DC Rainmaker's drain rate in max GPS with the screen always on projects to about 25 hours. No tester has yet let a PACE 4 die on that setting to check. That's more hours on paper than Garmin's 47 mm Forerunners claim. The GPS is the other headline. Side-by-side tests, six months of racing and a repeated-loop test all put its tracks among the cleanest here.
Maps arrived in the September 26 firmware. They're topo and landscape, non-routable, and squeezed into 4 GB of storage. COROS's own FAQ still says it doesn't do full mapping. That makes it the rare maker underselling its watch. Owners keep reporting that the silicone band's keeper works loose. The nylon strap is lighter anyway. Tom's Guide calls the watch comfortable even on skinny wrists. There's no tap-to-pay and no streaming music, only MP3 files you drag over.
The honest catch is heart rate. Three testing teams saw it follow a strap, or a Forerunner 970, closely on runs. The Quantified Scientist tested it through winter against a Polar H10. He found it poor and suspected cadence lock. Owners lean his way in the cold and on fast pickups. It pairs Bluetooth chest straps, which is the fix. For runners who train by pace, or who run somewhere with a real summer, we'd buy it. Choose the nylon strap.
COROS PACE 4Under $250Opens Amazon.com · Prices change often
Price band: under $250
Garmin sells the Forerunner 70 as the simple one, and it is. It's 43 mm and 1.4 oz (40 g), with five buttons. Garmin Coach run/walk plans and Training Readiness come at no extra cost. What Garmin doesn't shout about is how good the basics are. DC Rainmaker laid its single-band tracks over a multi-band Fenix 8 Pro's. He could barely tell them apart, downtown or on the trail. Its wrist heart rate held close to a chest strap, lagging only slightly when easing off between intervals. The Run Testers say it sits well on slender wrists.
The catch is everything it leaves out. There's no multi-band GPS, no music, no tap-to-pay and no barometer. So climb on a hilly run comes from GPS and reads low. If those are on your list, the 170 Music below has most of them. If a plan on your wrist is the point, we'd buy it. Our Forerunner 70 review has the full case, and our beginner's guide picks it too.
Garmin Forerunner 70Under $250Opens Amazon.com · Prices change often
Price band: under $350
It shares the Forerunner 70's small case, 1.68 in (42.6 mm) across. It's a gram heavier at 1.4 oz (41 g), and Garmin lists it for smaller wrists than the 970. The extra money buys music storage, Garmin Pay and a barometer. YouTube Music, Spotify, Deezer and Amazon Music all have watch apps for it, each needing its paid tier. Apple Music doesn't, on any Garmin. Testers found its heart rate accurate against a Polar H10. It lagged only in one interval session.
Garmin's manual is plain about the price of music. With a playlist running, GPS lasts 7.5 hours, against 20 without. That's enough for a marathon soundtrack, not a long day on the trail. Owners across Garmin's whole range report headphones cutting out once a run starts. Garmin's manual suggests trying the other wrist and swapping a metal or leather band for silicone. If your music lives in one of those four services and you want Garmin's training tools with it, we'd buy it. Our Forerunner 170 Music review covers the dropouts in detail. If you'd trade those training tools for spending less, our guide to choosing a Garmin points to the vívoactive 6 instead.
Garmin Forerunner 170 MusicUnder $350Opens Amazon.com · Prices change often
Price band: under $400
The smaller T-Rex 3 Pro packs what usually needs a big watch. Its free maps plan a new route when you miss a turn. It adds dual-band GPS, an LED flashlight and a sapphire lens, in a case 1.76 in (44.8 mm) across. The Quantified Scientist tested this exact size against a chest strap. Running heart rate tracked almost beat for beat, with brief cadence-lock moments. He preferred the smaller one on his own wrist. It's thicker than the Garmins. One owner reports workout heart rate getting stuck high after recent updates.
Then there's the spec sheet. Amazfit gives this size 26 hours of accurate GPS in one section and 29 in its comparison table. It gives no weight for it at all. A spec sheet with two figures for one number and none for another is the kind I'd send back to the supplier. Either figure is well short of the larger model's 38 hours. So the smaller case costs about a third of the battery, and nobody has run one down to check. If you hike or run trails and want maps on a slim wrist, we'd still buy it.
Amazfit T-Rex 3 ProUnder $400Opens Amazon.com · Prices change often
Price band: under $800
This is the full-size watch, and Garmin makes it in one size. It's 1.85 in (47 mm) across, 0.51 in (12.9 mm) thick and 2.0 oz (56 g). It earns a place here for one reason a slim-wrist runner cares about. It has the best measured wrist heart rate of any pick, near-identical to a chest strap on runs in The Quantified Scientist's test. It adds routable maps, an LED flashlight and sapphire. Garmin's battery table puts multi-band tracking at 21 hours. The drain Tom's Guide saw in a 10K race, screen always on, projects to about that.
The catch is the size, plainly. Two long-term reviewers wish Garmin made a smaller one. Tom's Guide says it still fits a slim wrist. If a 47 mm case sits flat on yours without overhanging, we'd buy it. We'd take it over the 47 mm Forerunner 570, which is the same size with fewer features. Our Forerunner 970 review has the rest.
Garmin Forerunner 970Under $800Opens Amazon.com · Prices change often
Garmin's Forerunner 70 and 170 arrived in May, both in the same small case. Both are picks above on months of independent testing. Apple's Ultra 4 (September) and Garmin's Enduro 4 (October) each come in one size. That's 49 mm at 2.2 oz (63.0 g) and 51 mm at 2.3 oz (66 g). We'd wait on both for full tests, but waiting won't shrink them.
The one to watch is Suunto's Run 2, the successor Suunto announced in September for runners who liked the Run's light, dual-band formula. Suunto says the Run 2 adds a few more hours of dual-band GPS than the Run, plus a brighter screen. Suunto's listing puts the Run 2 at 1.9 oz (53 g) on its silicone strap, against 1.3 oz (36 g) for the original Run. So the replacement got brighter and heavier at once. Nobody has measured one on a slim wrist yet.
We worked in four passes. First, case size, thickness and weight for each exact part number, claimed beside measured. Then heart rate tests on that same part number. Then what each watch gives up against its full-size sibling. Last, GPS hours in the maker's most accurate mode. A maker's claims were never enough by themselves. Every pick here rests on two different kinds of evidence about its own part number, and at least one comes from outside the maker. Our GPS battery planner works the hours out for your own longest day. No product recall touches any watch here.
Usually, but how much depends on the maker. Garmin's manual gives the 42 mm Forerunner 570 an hour less multi-band GPS than the 47 mm's 14. That's a fair trade for a smaller case. Amazfit's smaller T-Rex 3 Pro gives up about a third of the larger model's accurate-GPS hours. And small doesn't have to mean short. The PACE 4 claims 31 hours of dual-frequency GPS, where the 47 mm Forerunner 970 claims 21.
On steady runs, yes, provided the watch stays put. Light watches stay put. Heavy ones slide, which is what testers saw with the Vertical 2 and blamed on the Enduro 4. Wear it snug above the wrist bone, as Garmin's heart rate guidance says. Warm up first in the cold, as the Forerunner 570 manual advises. In the weight room, every watch here misses heart rate peaks, small or large. Use a chest strap there.
It may be. Garmin's manual gives it an hour less multi-band GPS than the 47 mm, and 10 days as a smartwatch. Owners with very small wrists report a good fit. One reviewer has weighed it, and testers of that size found its distance and heart rate on target. But that evidence sits in notes on the 47 mm's file, not in a checked record of its own. We haven't vetted the 42 mm the way we vetted the picks, so it isn't awarded here. The COROS APEX 4 42mm and the fēnix 9 43mm have no measurements at all, so they get no row. The 47 mm 570 we did research is covered in our Forerunner 570 review. It's the 970's size with fewer features. For a slim wrist, we'd skip it.
No. The lightest watch in our research is last generation's COROS PACE 3, at 1.1 oz (30 g) on nylon. But it has half the PACE 4's dual-frequency hours and no maps, and testers called its heart rate hit or miss. The vívoactive 6 is the thinnest on paper, and the Suunto Run is nearly as light. Both read heart rate less well on hard efforts. Light first, then the sensor, then the features you'd actually miss.
| Watch | Case across | Thickness | Weight | GPS hours, most accurate mode |
|---|---|---|---|---|
| COROS PACE 4View on Amazon (opens in a new tab) | 1.71 in (43.4 mm) | 0.46 in (11.8 mm) | 1.1 oz (32 g) on nylon | 31 h dual-frequency |
| Garmin Forerunner 70View on Amazon (opens in a new tab) | 1.69 in (43 mm) | Unchecked | 1.4 oz (40 g) | 16 h, single-band |
| Garmin Forerunner 170 MusicView on Amazon (opens in a new tab) | 1.68 in (42.6 mm) | Unchecked | 1.4 oz (41 g) | 14 h, single-band; 7.5 h with music |
| Amazfit T-Rex 3 Pro, smaller sizeView on Amazon (opens in a new tab) | 1.76 in (44.8 mm) | Unchecked | Not published | 26 h (29 h in Amazfit's other table) |
| Garmin Forerunner 970View on Amazon (opens in a new tab) | 1.85 in (47 mm) | 0.51 in (12.9 mm) | 2.0 oz (56 g) | 21 h multi-band |
Unchecked means reviewers or the maker print a figure, but it isn't yet in our checked registry for that part number.
Best for most slim wrists
Small wrists usually get offered the full-size watch's little sister. The good parts stay in the big one. The PACE 4 turns that around. The lightest watch we'd buy here carries the multi-band GPS and race battery that small watches usually leave behind. Put it on the nylon strap. Add a chest strap if winter heart rate matters to you. It's the small watch that doesn't ask you to settle.
COROS PACE 4Under $250Opens Amazon.com · Prices change often
Research count for this page: 17 models weighed; 10 maker manuals among them; across this site's research, 367 sources kept in full; 148 Reddit threads read, kept as the reader's summary, not in full.
Claimed figures are the maker's; measured figures name the tester. "Unchecked" means a figure exists in a review or on a maker page but not in our checked registry for that part number. Maker wrist ranges are left out of the table on purpose: every one of them is a strap length, and the 51 mm Enduro 4 lists nearly the same smallest wrist as the 42.2 mm vívoactive 6. Where a tester measured drain over part of a charge rather than running the battery flat, the hours are a projection and are labeled as one.
| Watch (exact variant) | Case across | Thickness | Weight | GPS, claimed (mode) | GPS, measured |
|---|---|---|---|---|---|
| COROS PACE 4 (W336) | 1.71 in (43.4 mm) claimed | 0.46 in (11.8 mm) claimed | 1.1 oz (32 g) nylon, 1.4 oz (40 g) silicone, claimed | 31 h dual-frequency (fewer with always-on); 41 h all systems | Drain in max GPS, always-on, projects to about 25 h; no rundown to empty (DC Rainmaker) |
| Garmin Forerunner 70 | 1.69 in (43 mm) claimed | Unchecked | 1.4 oz (40 g) claimed | 16 h all systems; 23 h GPS only | One hour in the best GPS mode used close to a tenth of the battery (TechRadar) |
| Garmin Forerunner 170 Music | 1.68 in (42.6 mm) claimed | Unchecked | 1.4 oz (41 g) claimed | 14 h all systems; 20 h GPS only; 7.5 h GPS with music | No GPS rundown |
| Amazfit T-Rex 3 Pro, smaller size | 1.76 in (44.8 mm) claimed | Unchecked | Not in our records | 26 h accurate GPS (29 h in the same page's table); 60 h long-battery mode | None on this size |
| Garmin Forerunner 970 | 1.85 in (47 mm) claimed | 0.51 in (12.9 mm) claimed | 2.0 oz (56 g) claimed; iRunFar's scale agreed within a gram | 21 h multi-band; 26 h GPS only | Drain in a 10K race, multi-band, always-on, projects to about 21 h (Tom's Guide) |
| Garmin vívoactive 6 | 1.66 in (42.2 mm) claimed | 0.43 in (10.9 mm) claimed; OutdoorGearLab measured it thicker, likely through the sensor bump | 1.3 oz (36 g) claimed; 1.3 oz (36.9 g) weighed (OutdoorGearLab) | 17 h all systems, no multi-band; 21 h GPS only | 20 h GPS only (OutdoorGearLab) |
| Suunto Run | 1.80 in (45.6 mm) measured (OutdoorGearLab) | 0.55 in (14.0 mm) in OutdoorGearLab's table; thinner in its own text and another review | 1.3 oz (36 g) claimed; 1.3 oz (36.9 g) weighed | 20 h dual-band | 19 h (OutdoorGearLab); 12 to 15 h in Alaska cold (CleverHiker) |
| Garmin Forerunner 165 | Not in our records | Not in our records | 1.4 oz (39 g) claimed | 17 h all systems; 19 h GPS only | Only on an edition testers didn't state |
| Amazfit Active Max | 1.91 in (48.5 mm) claimed | Unchecked | 1.4 oz (39.5 g) weighed without strap (T3) | 64 h, single-band | No rundown |
| Garmin Instinct 3 AMOLED (45 mm) | 1.77 in (45 mm) claimed | 0.59 in (14.9 mm) claimed | 1.9 oz (53 g) claimed | 23 h multi-band; 32 h GPS only | 30 h standard GPS (OutdoorGearLab) |
| Garmin Forerunner 570 (47mm) | 1.85 in (47 mm) claimed | 0.51 in (12.9 mm) claimed | 1.8 oz (50 g) claimed | 14 h multi-band; 18 h GPS only | None on a stated 47 mm |
| Apple Watch Ultra 4 | 1.93 in (49 mm) claimed | Unchecked | 2.2 oz (63.0 g) claimed | 18 h standard workout | About 18.6 h, extrapolated (DC Rainmaker) |
| Suunto Vertical 2 (steel) | 1.97 in (50.0 mm) measured (OutdoorGearLab) | 0.54 in (13.6 mm) claimed; OutdoorGearLab measured it thicker | 3.1 oz (87 g) claimed; 3.0 oz (85 g) weighed | 65 h multi-band | 66 h all systems (OutdoorGearLab) |
| Garmin Enduro 4 | 2.01 in (51 mm) claimed | 0.62 in (15.7 mm) claimed | 2.3 oz (66 g) claimed | 60 h multi-band | About 70 h, extrapolated from one outing (Bautsch Sportstec) |
| COROS PACE 3 | 1.65 in (42 mm) claimed | 0.46 in (11.7 mm) claimed | 1.1 oz (30 g) nylon, 1.3 oz (36 g) silicone, claimed | 15 h dual-frequency; 38 h GPS only | No test newer than 2023 |
| Garmin Forerunner 170 (non-Music) | 1.69 in (43 mm) claimed | Not in our records | 1.4 oz (41 g) claimed | 14 h all systems; 20 h GPS only | None on this edition |
| Samsung Galaxy Watch Ultra (2025), 47mm LTE | 1.85 in (47 mm) claimed | Unchecked | Not in our records for this edition | 48 h in power-saving exercise mode only | None on the 2025 unit |
The 42 mm Forerunner 570 (010-02970-00/-01/-02) has more evidence than we first credited. Garmin's manual gives its battery figures, owners with small wrists report a good fit, Live for the Outdoors weighed one, and testers of that size found its distance and heart rate on target and its always-on battery short of the 47 mm's. All of that sits in notes on the 47 mm's file rather than in a checked record of its own, so we show no figures for it and don't award it. The COROS APEX 4 42mm and the Garmin fēnix 9 43mm have no figures of any kind in this research, and results from the larger APEX 4 or the fēnix 9 Pro don't carry over to them. Most T-Rex 3 Pro reviews tested the larger size, so their battery and GPS results are kept off the smaller one. And every named heart rate and battery test on the Forerunner 170 used the Music edition, so the plain 170 has none of its own.
| Watch | Running heart rate | Tester and reference |
|---|---|---|
| COROS PACE 4 | Close to chest strap, spikes at start or after pauses; matched a Forerunner 970 in races | DC Rainmaker, Tom's Guide, The Run Testers |
| COROS PACE 4 | Poor on runs, suspected cadence lock; indoor cycling r 0.97 | The Quantified Scientist, Polar H10, winter |
| Garmin Forerunner 70 | Generally very good; slight recovery lag in intervals | DC Rainmaker, chest strap; TechRadar, Garmin and MyZone straps |
| Garmin Forerunner 170 Music | Accurate; lagged in one interval session | TechRadar, Polar H10; Tom's Guide, chest strap |
| Amazfit T-Rex 3 Pro, smaller size | r 0.97, with brief cadence-lock moments | The Quantified Scientist, Polar H10 |
| Garmin Forerunner 970 | r 0.98 | The Quantified Scientist, Polar H10 |
| Garmin vívoactive 6 | r 0.81, delays on rises; 1.0 bpm median on steady runs | The Quantified Scientist; OutdoorGearLab vs armband |
| Suunto Vertical 2 | r 0.88; 150 vs 151 bpm only after moving it up a slim wrist | The Quantified Scientist; Gadgets & Wearables |
| Garmin Enduro 4 | 89% of samples within 2 bpm on an easy run, 60% over a six-hour walk/run | Bautsch Sportstec, chest strap |
Every watch tested in the weight room missed heart rate peaks there.
| Watch | Why it lost here |
|---|---|
| Garmin vívoactive 6 | Thinnest by claim, and OutdoorGearLab's slim-wristed testers liked it. This page's reader wants the training tools and heart rate of a full-size running watch, and it gives up too much for that: single-band GPS, no barometer, no Training Readiness or triathlon mode, and an older sensor that lagged heart rate rises. Owners' biggest complaint is a screen that won't stay dark at night. For the least money for playlists on the wrist, though, it's the pick in our guide to choosing a Garmin. |
| Suunto Run | Light and dual-band, but heart rate was lackluster on hard track intervals, plans from Runna don't reach the watch, and Suunto has announced the Run 2 to replace it. |
| Garmin Forerunner 165 | Older software without Training Readiness; the Forerunner 70 is the better small Garmin. |
| Amazfit Active Max | Light for its size, but at 1.91 in (48.5 mm) across it's one of the widest watches here. It suits budget buyers with ordinary wrists, as in our Active Max review and budget guide. |
| Garmin Instinct 3 AMOLED (45 mm) | The smallest Instinct is still 0.59 in (14.9 mm) thick and heavier than any pick but the 970, with breadcrumbs instead of maps. That bulk is the problem on a slim wrist; a beginner who wants a screen that stays lit all week on buttons alone gets it from our beginner's guide. |
| Garmin Forerunner 570 (47mm) | The wrong size for this buyer; the 970 is the same case with maps and a flashlight. Racers who want music with multi-band GPS and have no use for maps are a different reader; see our Forerunner 570 review. |
| Suunto Vertical 2 | The heaviest watch here, and on a slim wrist it sits like a padlock on a shoelace; testers saw it slip. For bigger wrists and long trail days it has the longest measured battery in our GPS battery planner; see our Vertical 2 review. |
| Apple Watch Ultra 4 and Garmin Enduro 4 | New this autumn, one size each, 49 mm and 51 mm. We'd wait for full tests. |
| COROS PACE 3 | The lightest watch in our research, but last generation, with 2023-era heart rate testing, no maps and half the PACE 4's dual-frequency hours. It was the model most hit by COROS's May 2026 update failures, for which COROS replaced dead watches. |
| Garmin Forerunner 170 (non-Music) | The 170 Music's case without the music; its test results belong to the Music edition. |
| Samsung Galaxy Watch Ultra (2025) | 47 mm, Android only, and its lab results come from the 2024 unit. |
| Question | What the sources say | Status |
|---|---|---|
| PACE 4 heart rate | Good for DC Rainmaker, Tom's Guide and The Run Testers; poor for The Quantified Scientist in winter. Temperature, fit and individual wrists are the likely explanation, and owners side with the winter result in the cold. | Open |
| PACE 4 maps | Testers before September 2026 and COROS's FAQ say no maps; the September 26 firmware (V3.2008.0) added them. | Explained |
| T-Rex 3 Pro GPS hours, smaller size | Amazfit prints 26 h and 29 h on the same page. | Open |
| Suunto Run thickness | OutdoorGearLab's table and text disagree, as does CleverHiker; likely the sensor bump. | Open |
| vívoactive 6 and Vertical 2 thickness | Both measured thicker than claimed, most likely through the sensor bump. | Explained |
| Forerunner 70 GPS battery | TechRadar's one-hour sample suggests well under Garmin's all-systems claim; one sample, brightness not stated. | Open |
| Forerunner 970 always-on battery | 2.5 days on launch firmware at default brightness (DC Rainmaker) against 4 to 6 days later at lower brightness (Tom's Guide, DesFit). | Explained by firmware and brightness |
| Recalls | The CPSC database returned none for Garmin, COROS, Amazfit, Suunto, Apple Watch or Samsung Galaxy Watch. | Settled |
How we research
Milewright doesn't test watches. It sets each maker's claim against what labs, reviewers and owners measured on the exact same model, and tells you which number to believe.
By price band
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