For most people training for and running a marathon, our pick is the COROS PACE 4, an ultralight GPS watch that handles long training blocks and race-day pacing without fuss. If you want the gentlest learning curve and a big app ecosystem, the Garmin Forerunner 55 is the easier first watch. And if you genuinely only need to start, stop, and record splits, a simple device like the Marathon Adanac 8000 stopwatch does that one job and nothing else.
The short answer: which to pick for a marathon
A marathon asks three things of a timing device: keep accurate pace and distance over hours, last the whole race on one charge, and show you the one or two numbers you actually run by. Two of the options here are wrist-worn GPS running watches built for exactly that, and the third is a handheld stopwatch built for simple timing. So the real decision is less about brand loyalty and more about how much guidance you want while you train.
Across a full training cycle and on race day, the COROS PACE 4 stands out as our pick. It is a lightweight GPS sport watch, which matters more than it sounds like it should when a watch is on your wrist for three, four, or five hours. It tracks pace, distance, and your run history so you can hold an even effort instead of going out too fast, the single most common marathon mistake. For a first-timer who wants the watch to suggest workouts and hold their hand a little more, the Garmin Forerunner 55 is a friendlier starting point.
COROS PACE 4 Ultralight Sport GPS Watch
Our overall pick for marathon training and racing: an ultralight GPS watch that keeps steady pace and distance over long hours, so you can run by effort instead of guesswork.
Check price on AmazonWhichever you choose, treat the numbers as guidance. Build your mileage gradually, warm up before hard sessions, train within your current ability, and check with a doctor or a qualified coach before starting a new program, especially if marathon distance is new to you.
When each pick is the better choice
These three are not really rivals so much as answers to different questions. Here is how we would match them to a runner.
Choose the COROS PACE 4 if you want a focused running watch that feels almost weightless on long runs, tracks pace and distance cleanly, and gives you training data without a lot of clutter. It suits runners who already know they want GPS and care about holding a target pace over the back half of the race, where discipline wins or loses a marathon.
Choose the Garmin Forerunner 55 if this is your first structured training block and you want the watch to offer daily suggested workouts and a very large, well-known app and accessory ecosystem. Its listing advertises up to two weeks of battery life in everyday use, which means less charge anxiety between runs, and Garmin's platform is familiar to a lot of running clubs and friends who can help you set it up.
Choose the Marathon Adanac 8000 stopwatch if you do not want a GPS watch at all. It is a professional handheld digital stopwatch with touch feedback, the kind of tool a coach, a race volunteer, or a track official uses to time runners and record lap splits. It will not map your route or estimate your pace per mile, but for pure elapsed-time timing it is simple, rugged, and distraction-free.
What actually matters for a marathon watch
It is easy to get pulled toward feature lists. For 26.2 miles, only a handful of things change your experience.
GPS accuracy. Pace and distance on any GPS watch are estimates, not laboratory measurements. They can drift under tree cover, between tall buildings, or on an out-and-back course. For marathon pacing this is usually close enough to be useful, but do not panic if your watch reads slightly long or short against the official course markers. Learn how your watch behaves on your regular routes and trust effort as much as the screen.
Battery life for long runs. This is where a dedicated running watch earns its place. A full GPS session for several hours needs a watch that will not die at mile 22. Both the COROS PACE 4 and the Garmin Forerunner 55 are built to record a marathon on a single charge with margin to spare, and the Garmin listing quotes up to two weeks in smartwatch mode, though active GPS always drains a battery far faster than standby. A simple stopwatch, by contrast, sips power and runs for a very long time on a small cell.
Pacing and training metrics. The reason to wear a GPS watch is to run smarter. Seeing your current pace, average pace, and distance in real time helps you avoid the classic too-fast start. Over a training block, your run history shows whether your easy runs are truly easy and your long runs are building. The Garmin Forerunner 55's daily suggested workouts add a layer of structure for people who do not want to design their own plan. Remember that any readiness, recovery, or fitness estimate a watch shows is a training aid, not a medical readout.
Screen and readability. On tired legs at the end of a long run, you want to glance down and read your pace instantly. Both running watches here show the core numbers clearly. A stopwatch shows one thing, big and plain, which is its own kind of readability.
What to ignore. Do not buy for features you will never open during a marathon. Fancy dashboards, dozens of sport modes, and social sharing are nice but they do not get you to the finish line. For marathon running specifically, accurate pace, reliable distance, enough battery, and a clear screen matter far more than a long spec sheet.
How the three compare
Think of them as three steps on a single ladder of complexity. The Marathon Adanac 8000 is the simplest rung: a dependable handheld timer with no GPS, no pace, and no training history. If you have a measured track or you only care about your total finishing time read off a clock, it does the job and never needs a phone.
The Garmin Forerunner 55 is the middle rung and, for many beginners, the most reassuring. It brings GPS, pace, distance, daily suggested workouts, and long everyday battery life inside a familiar ecosystem, so there is lots of help available when you get stuck. It is a watch you can grow into for a first marathon and well beyond.
The COROS PACE 4 is the rung for the runner who wants a light, focused tool that gets out of the way. It covers the same core running job as the Garmin and leans into being an unobtrusive, lightweight GPS watch for people who live by their pace. Between the two GPS watches, we would choose the COROS PACE 4 for the runner who prioritises comfort over hours and clean pacing data, and the Garmin Forerunner 55 for the runner who wants guided workouts and the widest support network.
If you are still deciding across the category, our running watches hub collects more comparisons so you can weigh the trade-offs before you commit.
Our honest verdict
For the widest range of marathon runners, from a first-timer chasing a finish to a repeat runner chasing a time, our pick is the COROS PACE 4. It is light enough to forget on long runs, it tracks the pace and distance that keep you honest, and it holds a charge long past the finish line. We would hand it to someone who already knows they want a GPS watch and wants it to stay out of the way.
If you are brand new to structured training and want the watch to suggest sessions and plug into a huge ecosystem of apps, accessories, and knowledgeable friends, the Garmin Forerunner 55 is the kinder on-ramp, and its long everyday battery life means one less thing to think about. And if you have read this far only to realise you do not want a GPS watch at all, there is no shame in that: the Marathon Adanac 8000 is an honest, no-frills stopwatch that times a run and records splits without ever asking to be charged overnight or paired with your phone.
Whatever you pick, the watch is a tool, not a training plan. Progress comes from consistent, gradual work, proper warm-ups, running within your ability, and sensible rest. Treat every on-watch metric as an estimate and an aid, not a diagnosis, and talk to a qualified professional before taking on a new distance. Browse the running watches hub if you want to compare a few more options before race day.