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The quick answer
Best triathlon watch, sprint to Ironman
Opens Amazon.com · Prices change often
Garmin Forerunner 570 – 47mmThe same race software for one band lessUnder $600
Garmin Instinct 3 – 45 mm, AMOLEDBest buttons-only triathlon watch under $350Under $350
COROS PACE 4Best triathlon watch under $250Under $250Price bands, not prices
| Watch | Verdict | Who it suits | The catch | Price band and link |
|---|---|---|---|---|
 Garmin Forerunner 970Our pick | Best triathlon watch, sprint to Ironman | Triathletes building to a full Ironman who want automatic transitions and battery to spare | Open-water tracking is its weakest leg, and testers disagree on how weak | Under $800View on Amazon (opens in a new tab) |
| Garmin Forerunner 570 – 47mmBuy | The same race software for one band less | Triathletes racing sprints to 70.3s, or a full Ironman finished inside its multi-band hours | 14 hours of multi-band GPS claimed, which a long Ironman day can outlast | Under $600View on Amazon (opens in a new tab) |
| Garmin Instinct 3 – 45 mm, AMOLEDBuy | Best buttons-only triathlon watch under $350 | Triathletes on a tighter budget who want automatic transitions, ANT+ sensors and no touchscreen at all | No tester has published a swim result for this exact 45 mm watch | Under $350View on Amazon (opens in a new tab) |
| COROS PACE 4Buy | Best triathlon watch under $250 | First-time triathletes who want long battery, multi-band GPS and a tested open-water track on a small budget | No automatic transitions: you press the dial to change legs | Under $250View on Amazon (opens in a new tab) |
| COROS PACE 4 ProWait | New: wait for the battery fix | COROS fans who want the big bright screen and the long battery claim, once it holds | Measured GPS battery falls well short of its claim until COROS ships a fix, and no swim test exists yet | Under $450 |
| Apple Watch Ultra 4Wait | New: wait, even on iPhone | iPhone owners who want one watch for racing and daily life | Ending a workout takes a tap that testers found unreliable wet, and its only swim test had no reference | Under $800 |
COROS PACE 4 Pro
Apple Watch Ultra 4
COROS PACE 4Best triathlon watch under $250
Garmin Instinct 3 – 45 mm, AMOLEDBest buttons-only triathlon watch under $350
COROS PACE 4 ProNew: wait for the battery fix
Garmin Forerunner 570 – 47mmThe same race software for one band less
Garmin Forerunner 970Best triathlon watch, sprint to Ironman
Apple Watch Ultra 4New: wait, even on iPhone
Every triathlon watch on the shelf promises three sports. The race is won or lost in the fourth. That's the transition tent, where you're wet, half out of a wetsuit and stabbing at a button with a numb thumb. Milewright's pick for a triathlete going from first sprint to full Ironman is the Garmin Forerunner 970. It changes legs by itself. It shuts off its touchscreen the moment you hit the water, and it pairs your bike's power meter. Garmin rates it at 21 hours with both GPS bands on, and the drain measured in a race projects to about the same. That's a long Ironman with daylight to spare. The catch is the swim. Open-water tracking is its weakest skill, and the two testers who measured it disagree on how weak. Our Forerunner 970 review has the full battery-by-firmware story.
Garmin Forerunner 970Under $800Opens Amazon.com · Prices change often
Three things move you down the ladder. Racing nothing longer than a 70.3? The Forerunner 570 runs the same triathlon software for one price band less. Capped at the under $350 band? The Instinct 3 AMOLED keeps automatic transitions and ANT+ sensors, and drops the touchscreen entirely. Capped at the under $250 band? The COROS PACE 4 has the longest battery here and a tested open-water track, but you change legs yourself. And if you hoped one Apple Watch could do it all on your iPhone, the new Ultra 4 isn't that watch yet.
Price band: under $800
The box says 21 hours with both GPS bands tracking. No tester has yet drained a 970 to empty with both bands on, but the evidence points the right way. In a measured 10K race, the 970's drain projects to about 21 hours, right where the box puts it.
The race software is the real reason to buy it. Its manual times transitions separately by default. An optional Auto Sport Change spots the swim exit and the bike dismount on its own. A Lock Device setting freezes the touchscreen and buttons for the whole race. Put those together and the watch runs your day without you touching it. It also has maps and a real LED flashlight, which you'll appreciate at 5 a.m. in a transition area lit like a mall parking lot.
Its weak leg is the water, and here the evidence splits. DC Rainmaker swam in the sea, stopping on purpose to tread water. He found tracks worse than Garmin's recent watches, and on a later firmware he called it "getting worse". the5krunner swam one calm lake lap in a wetsuit. His track came out just 1.6% long, smoothed straighter than he actually swam. Both can be true. Swim steadily in a wetsuit and you'll get something close. Stop at a crowded buoy and the track wanders. Pool counts come only from owners, who report extra and missing lengths on more than one firmware.
If you're building toward a full Ironman and can stretch to this band, we'd buy it.
Garmin Forerunner 970Under $800Opens Amazon.com · Prices change often
Price band: under $600
Strip the maps, flashlight and sapphire off a 970 and you have the 570. The triathlon brain is the same. Its manual carries the same Auto Sport Change, the same touchscreen shutoff in the water and the same Lock Device setting. One quirk: it says to hold the lap button at each transition, where the 970's says press. The 570 manual also asks you to avoid pressing buttons under water. That's sound advice for a watch you'll be jabbing at while still knee-deep.
The difference that matters is battery. For the 47mm with both bands locked on, the manual's figure is 14 hours. That covers any sprint, Olympic or 70.3 with room left over. If your full Ironman will run longer, switch to Auto Select (16 hours claimed) or GPS Only (18 hours) before the gun.
The swim evidence is thin. DC Rainmaker swam one 570 beside a 970, and it came out a touch better. He put that down to luck, and he never said which case size he wore. On the 47mm itself, open-water and pool accuracy are not measured. Our 570 vs 970 comparison covers what else the step up buys, and the Forerunner 570 review covers living with it.
For triathletes whose races finish inside its multi-band hours, we'd buy it.
Garmin Forerunner 570 – 47mmUnder $600Opens Amazon.com · Prices change often
Price band: under $350
There's no touchscreen at all, just five buttons. That's the right answer to a wet thumb. Garmin's spec sheet gives it triathlon and swimrun profiles with automatic transitions. It pairs power meters over ANT+ and Bluetooth. Its 10 ATM rating is the toughest on this ladder.
In standard GPS mode, the box tells the truth: Garmin says 32 hours, and OutdoorGearLab got about 30 on this exact watch. Nobody has yet run one down on multi-band. There Garmin claims 23 hours, with SatIQ choosing when it needs both bands, which would cover a long Ironman if it's close. Wrist heart rate tracked a chest strap respectably on runs and rides.
Here's the honest gap. Nobody has published a swim test on this exact 45 mm watch. DC Rainmaker found an AMOLED Instinct 3 stayed accurate in open water, but he didn't say which size he wore. That's encouraging, not proof.
If you want Garmin's race software on a tighter budget and prefer buttons to glass, we'd buy it.
Garmin Instinct 3 – 45 mm, AMOLEDUnder $350Opens Amazon.com · Prices change often
Price band: under $250
On COROS's battery page, dual-frequency tracking is rated at 31 hours with raise-to-wake, and a little less with the screen always on. DC Rainmaker's own PACE 4, display lit throughout on its most accurate GPS setting, used about 4%/h. That projects to about 25 hours. It's an Ironman with the display lit the whole way, from the cheapest watch on this page.
It's also one of only five watches we weighed with any open-water test on the exact model. The verdict was "acceptable", with one corner cut badly, which for COROS counts as a good day. One owner logged sixteen long pool sessions without a miscounted length. That's one person's report, not a test. At 1.4 oz (40 g) on the silicone strap, it disappears under a wetsuit sleeve.
The catch is transitions. COROS's own triathlon guide has you press the dial and choose Transition at each change. It describes no automatic sport detection. It's a general COROS article rather than a PACE 4 page, but nothing suggests this watch does better. Check your sensors too: COROS documents Bluetooth heart-rate straps and says nothing about ANT+.
For a first triathlon on a small budget, we'd buy it. The PACE 4 review has the battery on current firmware. COROS vs Garmin sets it against the Garmins at each price.
COROS PACE 4Under $250Opens Amazon.com · Prices change often
Two new watches matter to triathletes, and neither has earned a place yet. Nothing measured on an older model carries over to them. Garmin's new fēnix 9 (47 mm) and Enduro 4 have triathlon modes too. Every swim result so far belongs to fēnix 9 Pro units or to nobody, so we're waiting on a test of either exact watch.
Price band: under $450
COROS's product page shows an example Ironman of 11 h 48 min, finished with 73% left. It's a lovely number with no GPS mode printed beside it. I treat a figure like that the way I'd treat fuel economy measured on the way down a mountain. With multi-band and the screen always on, DC Rainmaker's measured drain projected under 20 hours. The battery page promises 30 for exactly that combination, so more than a third of the claim went missing on the wrist. COROS blamed bugs and said a fix would ship this month. When we last read its release notes, on 30 October, they still listed only the September build. Transitions are manual and sensors are Bluetooth only. Nobody has swum a measured lap with it yet, though two testers have open-water results due. Wait for the fix and the swim tests.
Price band: under $800
Apple's multisport mode spots transitions automatically. Water Lock switches on when a swim starts. Apple rates a workout at 18 hours, and DC Rainmaker's measured drain projects to about 18.6. That covers an Ironman only if you're quick or careful with settings. Ending a workout takes a tap, which he found unreliable wet and hopeless in gloves. Its one swim so far came out more jagged than a fēnix 9 Pro's, with no independent reference. Apple's strong open-water record was set by the Ultra 3, and a record doesn't come in the box with the next model. It's iPhone only. Wait for a referenced open-water test and a race transition test on the Ultra 4 itself.
We ranked what each price step buys a triathlete: automatic transitions, power meters, buttons or touch in the water, and battery for your longest race. Then we counted the swim evidence on each exact model. The count is sobering. Of the 14 models we weighed, only five have any open-water test on the exact watch, and the Ultra 4's single swim had no reference to judge it against. Only the Forerunner 970 has two testers. Not one has a published pool lap-count test, so every lap claim here comes from owners. Safety doesn't separate them either: the CPSC's recall database lists nothing for Garmin, COROS or Apple Watch.
Not for a sprint. Even with them, the watch won't match the official clock. Garmin's auto transitions start T1 when you stop swimming, not when you cross the mat, so the watch's T1 reads long. Want splits that match the results sheet? Both Garmin manuals offer the lap button at the start and end of each transition. What automatic transitions buy you is not having to remember. By mile 80 of the bike, that's worth more than it sounds.
On multi-band GPS, measured drain puts the 970 and the PACE 4 through a long day. The Instinct 3 gets there on Garmin's claim, which nobody has tested on multi-band yet. The 570 covers yours if you'll finish inside 14 hours, or longer on a lower GPS setting. Put your expected finish time into the GPS battery planner to see how much margin each watch leaves.
Less tested than anything else these watches do. The 970's track is close when you swim steadily and wanders when you stop. The PACE 4's is acceptable, with the odd cut corner. On the 570 47mm and Instinct 3 45 mm, it simply isn't measured. Treat swim distance as a training log, not a split to argue with a race official.
On the Garmins, yes. The 570 and Instinct 3 pair ANT+ and Bluetooth meters, and the 970 recorded a power meter ride in testing. COROS documents only Bluetooth sensors for the PACE watches. If your power meter is ANT+ only, stay on the Garmin rungs.
Garmin's manuals switch the touchscreen off during swims and offer Lock Device for the whole race. That matters on the 970, which has a long-running forum thread about ghost touches, handled by replacing the watch. The Instinct 3 sidesteps the question with buttons only. The PACE 4 locks itself by default until you hold a button.
| Watch | Price band | Changes legs itself | Bike power meters | Swim tests on this exact model | |
|---|---|---|---|---|---|
| Garmin Forerunner 970 | under $800 | Yes | Yes, used in testing | Open water: two testers, split. Pool: not measured | View on Amazon (opens in a new tab) |
| Garmin Forerunner 570 (47mm) | under $600 | Yes | ANT+ and Bluetooth | Not measured | View on Amazon (opens in a new tab) |
| Garmin Instinct 3 AMOLED (45 mm) | under $350 | Yes | ANT+ and Bluetooth | Not measured | View on Amazon (opens in a new tab) |
| COROS PACE 4 | under $250 | No, press the dial | Bluetooth straps; ANT+ not stated | Open water: one tester, acceptable. Pool: not measured | View on Amazon (opens in a new tab) |
| COROS PACE 4 Pro | under $450 | No, press the dial | Bluetooth only | Not measured | Wait for the battery fix |
Best triathlon watch, sprint to Ironman
Buy the watch that gets the boring parts right. The 970 changes legs without being asked and keeps its screen out of the water. It talks to any power meter. It still has battery when the finish line lights come on. Its swim track is the part we'd forgive, because nobody has yet proved a rival swims better on the exact model you'd buy. Read the Forerunner 970 review before race day. Then let it run the transitions while you run the race.
Garmin Forerunner 970Under $800Opens Amazon.com · Prices change often
Research count for this page: 14 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.
| Watch (exact) | Band | Triathlon mode and transitions | Power meters | Controls in the water | Open water on this exact model | Pool laps on this exact model | Where it landed |
|---|---|---|---|---|---|---|---|
| Garmin Forerunner 970 | under $800 | Yes; Auto Sport Change optional, otherwise press lap (manual) | Used in DC Rainmaker's ride test | Touch plus buttons; touch off in swims; Lock Device | DC Rainmaker, several sea swims: weaker than recent Garmins, "getting worse" on retest. the5krunner, one lake lap: 1.6% long | Not measured by a tester; owner errors on fw 15.52 and 17.33 | Winner |
| Garmin Forerunner 570 (47mm) | under $600 | Yes; Auto Sport Change optional, otherwise hold lap (manual) | ANT+ and Bluetooth | Same as 970 | Not measured (one DC Rainmaker swim, case size not stated) | Not measured; one forum report, size not stated | Pick |
| Garmin Instinct 3 AMOLED (45 mm) | under $350 | Triathlon and swimrun, auto transition | ANT+ and Bluetooth | Five buttons, no touchscreen; 10 ATM | Not measured (DC Rainmaker's AMOLED unit, size not stated, was accurate) | Not measured | Pick |
| COROS PACE 4 | under $250 | Yes; manual transitions per COROS's general guide | Bluetooth straps documented; ANT+ and power meters not stated | Touch plus three buttons; Hold to Unlock by default | DC Rainmaker: acceptable, cut one corner | Not measured; one owner, no miscounts over sixteen sessions | Pick |
| COROS PACE 4 Pro | under $450 | Yes; manual transitions per COROS's general guide | Bluetooth only | Touch plus three buttons; swim lock not stated | Not measured; tests announced | Not measured; one review says "strong" with no counts | Wait (new) |
| Apple Watch Ultra 4 | under $800 | Multisport, automatic transitions | Bluetooth | Water Lock automatic; ending a workout needs a tap | One lake loop, no reference: more jagged than a fēnix 9 Pro | Not measured | Wait (new) |
| Garmin fēnix 9 (47 mm, base) | under $1,000 | Yes | ANT+ and Bluetooth | Touch plus five sealed inductive buttons; 10 ATM | Not measured on the base model | Not measured | Considered: new, watching |
| Garmin Enduro 4 | under $900 | Yes, auto transition | ANT+ | Touch plus buttons; 10 ATM | Not measured | Not measured | Considered: new, watching |
| Polar Vantage M3 | under $500 | Multisport; press BACK to change sport (Polar support) | Bluetooth only | Touch plus five buttons | Not measured | Owners: length counting works; stroke detection split | Considered |
| COROS APEX 4 (46mm) | under $500 | Yes | Bluetooth only, no ANT+ | MIP touch plus three buttons | DC Rainmaker: undercut the course | Not measured | Left out |
| Suunto Run | under $200 | Fixed triathlon profile, not customizable | Bluetooth, added by July 2025 firmware | Touch plus buttons | DC Rainmaker: poor | Not measured | Left out |
| Garmin vívoactive 6 | under $300 | No triathlon profile (manual) | Not relevant | Touch plus buttons | Not measured | Not measured | Left out |
| Garmin Forerunner 70 | under $250 | No triathlon or open-water mode | No | Touch plus buttons | No open-water mode | Not measured | Left out |
| Garmin Forerunner 170 | under $300 | No triathlon mode | Yes | Touch plus buttons | Not measured | Not measured | Left out |
The COROS APEX 4 (46mm) is a superb watch for long days on the trail, as our APEX 4 review says, but for triathlon it lacks ANT+, its open-water track undercut the course, and COROS itself pitches the PACE line at triathletes. The Suunto Run tracks well on land, yet its open-water track was "barely acceptable if you only swam once a year" and its triathlon profile can't be changed.
Three Garmins never had a chance because none of them has a triathlon profile. The Forerunner 70 also lacks open-water swimming and power meters; it's the first running watch we'd buy, as our Forerunner 70 review explains, and the wrong one for a triathlon. The vívoactive 6 and Forerunner 170 fall short on the same missing profile.
We weighed the Polar Vantage M3 on its evidence and left it out: owners find its pool length counting sound, but you change sport by hand, its sensors are Bluetooth only, and no tester has measured its open-water swim.
The fēnix 9 (47 mm) and Enduro 4 are new, so they sit on our watch list rather than in the skip pile. Every published swim result on the fēnix 9 line comes from Pro units, mixed between a spot-on track and a struggling one on the same swim, while the Enduro 4 has no swim test at all and comes only in a 51 mm case.
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.
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