The Forerunner 255 brings a bunch of advanced features—music storage, Garmin Pay, better sleep tracking, and deeper training metrics—while the Forerunner 55 sticks to the essentials at a friendlier price. Both watches nail GPS tracking and battery life, but they’re definitely aimed at different types of runners.
After testing both, I’ll walk you through the key differences in design, navigation, training tools, and real-world performance. If you’re new to GPS watches or just want more data, knowing what sets these apart will help you decide which Garmin fits your style and budget.
Key Differences Between Garmin Forerunner 55 and 255
The FR55 usually costs about £200 and focuses on the basics for running. The Forerunner 255 starts at £350 and packs in extra training tools and smart features.
The price gap is mostly about sensors, battery life, and more detailed performance tracking.
Feature Overview
The Forerunner 255 is loaded with sensors. I found the altimeter, compass, and thermometer especially handy for trail runs and elevation tracking.
It also has a pulse oximeter for blood oxygen readings—something the FR55 just doesn’t offer.
Battery life is another biggie. The 255 lasts almost twice as long in GPS mode compared to the 55.
The 255 Music version holds about 500 songs right on the watch. The FR55? No music storage at all.
Smart features:
- Garmin Pay (contactless payments)
- Text responses (Android only)
- Dual-frequency GPS for better accuracy
- Advanced running dynamics
The Forerunner 55 sticks to basic notifications and standard GPS. Both sync with the Garmin Connect IQ app and let you swap out watch faces.
Price and Value
The Garmin Forerunner 55 often drops to about £170 on sale. The 255 stays near its £350 launch price.
That extra £180 buys you a lot, especially if you want the advanced sensors and training tools.
The FR55 is a great deal for beginners. It gives you the core running stats without drowning you in data.
For experienced runners, the 255’s training load and performance condition features are huge. These help you avoid overtraining and recover smarter.
Value comparison:
- FR55: Best for budget-focused beginners
- 255: Worth it for serious runners looking long-term
Who Each Watch Is For
The Garmin Forerunner 55 is perfect if you’re just starting out. Its simple interface won’t trip you up if you’re new to GPS watches.
I’d pick the FR55 for casual runners who just want pace, distance, and heart rate. It’s great for 5Ks up to half-marathons.
The Forerunner 255 is aimed at more committed athletes. Trail runners, in particular, will love the altimeter and compass.
If you’re training for a marathon, the 255’s advanced stats—like training readiness and HRV—really help manage tough training blocks.
Go with the FR55 if you:
- Run a couple times a week
- Just want simple, reliable tracking
- Prefer basics over lots of features
Go with the 255 if you:
- Train for marathons or ultras
- Run trails or mixed terrain
- Want in-depth performance analysis
Design, Display, and Comfort
Both watches have that classic round face and five-button layout. The Forerunner 255 gives you more size options and a sharper screen, while the 55 keeps it straightforward with just one size.
Sizes and Fit
The Forerunner 55 comes in a single 42mm size. Personally, it fits most wrists without looking oversized.
It measures 42 x 42 x 11.6mm, weighs only 37 grams, and the strap fits wrists from 126mm to 203mm.
The Forerunner 255 comes in two sizes: 41mm and 46mm. The bigger one is 45.6 x 45.6 x 12.9mm and weighs 49 grams.
Having both sizes is nice. The smaller 41mm is a bit lighter, so you can pick what feels best.
Both watches have a sporty look and physical buttons that are easy to use, even when you’re sweaty.
Resolution and Screen Quality
The Forerunner 55 has a 26.3mm display with 208 x 208 pixels. It’s full color and easy to read while running.
The Forerunner 255 bumps it up to a 33mm display and 260 x 260 resolution. Text and numbers look noticeably crisper.
Both screens are bright enough for outdoor use. I find the 255’s larger display makes it easier to glance at multiple stats mid-run.
Color is solid on both, and they’re readable in all sorts of lighting.
Materials and Bands
They both use sturdy polymer cases. The silicone bands are comfy and handle sweat without any issues.
Both are waterproof to 5 ATM (50 meters), so swimming is no problem.
Quick-release bands make swapping straps easy. You can use standard 20mm bands if you want to change up the look.
The build quality feels good on both. I haven’t had any durability issues with the polymer cases so far.
GPS and Navigation Features
The Forerunner 55 and 255 handle GPS pretty differently. The 255’s navigation tools and sensors are a big step up over the 55.
Satellite Systems and Accuracy
The Forerunner 55 uses standard GPS, GLONASS, and Galileo. It’s fine for most runs, but accuracy can wander a bit on longer outings.
If you’re on trails or need really precise tracking, it’s not quite enough.
The Forerunner 255 uses dual-frequency GPS, grabbing signals from two bands at once for better accuracy.
It connects to GPS, GLONASS, Galileo, and multi-frequency systems. Tracking stays solid even in forests or cities with tall buildings.
For trail running or skiing, I noticed the 255 really shines. You can also upload specific routes to follow.
The 255 has a “back to start” feature if you get lost. The 55 doesn’t offer any navigation like that.
Barometric Altimeter and Sensors
The Forerunner 55 skips the barometric altimeter, compass, and thermometer.
This makes it less useful for trail running or skiing, where elevation data is important. You’ll miss out on some metrics that rely on elevation change.
The Forerunner 255 has a barometric altimeter, compass, gyroscope, and thermometer.
These extras are great for outdoor activities. The altimeter is especially helpful for running power and accurate elevation stats.
For hiking or skiing, the compass and thermometer come in handy. The altimeter can even help predict weather by tracking pressure changes.
Performance and Training Tools
The Forerunner 255 brings a lot more to the table for training and performance. It covers multisport support, detailed recovery, and advanced stats like training load and HRV that the 55 just doesn’t have.
Workout Modes and Sports Profiles
The Forerunner 55 focuses on running and basic fitness. It covers the essentials and even has swimming profiles, which is nice if you cross-train sometimes.
The Forerunner 255 supports way more sports. I used it for outdoor running, strength training, and cycling—options you won’t find on the 55.
Key differences:
- 55: Running, cycling, swimming, treadmill
- 255: Triathlon, trail running, track running, pool and open water swimming, strength, yoga
The 255 is better if you do a mix of sports. The 55 is great if you mostly run with the occasional other workout.
Advanced Metrics and Analytics
This is where things really split. The Forerunner 55 gives you basics: pace, distance, heart rate zones.
The 255 adds advanced metrics I’ve come to rely on:
- Training Load: Tracks how hard you’re working over time
- VO2 Max: Estimates aerobic fitness
- Race Predictor: Guesses finish times for common race distances
- Lactate Threshold: Finds your anaerobic pace
- Vertical Oscillation: Measures your running form
- Recovery Time: Suggests rest between hard efforts
The 255 also has PacePro for pacing on hilly courses. The 55 doesn’t offer these deeper analytics.
Triathlon and Multisport Support
The Forerunner 55 doesn’t handle triathlon or multisport. You’d have to start and stop activities manually.
The Forerunner 255 has dedicated triathlon modes. It transitions automatically between swim, bike, and run—super helpful on race day.
The 255 tracks transition times and keeps stats for each sport, while also showing your total race time.
Health Monitoring
Both watches cover heart rate, but the 255 goes much further with health tracking.
Forerunner 55 includes:
- All-day heart rate
- Sleep tracking
- Stress tracking
Forerunner 255 adds:
- HRV status
- Body Battery (energy monitoring)
- Pulse Ox (blood oxygen)
- Health Snapshot (quick wellness check)
- Morning Report (overnight recovery)
The Body Battery on the 255 is actually useful for planning workouts. HRV status gives you recovery insights that the 55 just doesn’t have.
Smartwatch and Music Features
The Forerunner 255 acts more like a true smartwatch, with music storage and Garmin Pay. The Forerunner 55 keeps it simple—just notifications, no music or payments.
Notifications and Daily Use
Both watches handle smartphone notifications pretty well with the Garmin Connect app. I get texts, calls, and app alerts right on my wrist, no fuss.
The Forerunner 55 covers the basics. You can read messages and see who’s calling, but there’s no way to reply from the watch itself.
The Forerunner 255 pushes things a bit further. It gives you the same notifications, but you get a few more ways to tweak how they show up in the settings.
Smart features comparison:
- Weather updates: Both models show current conditions
- Calendar sync: Available on both watches
- Find my phone: Standard on both devices
Neither watch runs third-party apps like a full-on smartwatch. They’re really fitness-first, with smart extras thrown in.
Music Storage and Streaming
This is where you see a big difference. The Forerunner 55 just doesn’t do music—no storage, no streaming, nothing.
The Forerunner 255 Music (there’s a plain version too) lets you store up to 500 songs right on the watch. I can sync playlists from Spotify, Deezer, or Amazon Music straight to it.
Music features on Forerunner 255 Music:
- 500+ song storage capacity
- Spotify, Deezer, Amazon Music support
- Bluetooth headphone connectivity
- Offline listening during runs
Music syncs over Wi-Fi when the watch is charging. It takes a little while if you’re moving big playlists, but honestly, once it’s set up, it just works.
If you like running without your phone, the music storage is a game changer. I leave my phone at home and still have my favourite tracks in my ears.
Contactless Payments
The Forerunner 55 doesn’t do payments at all. You’ll have to bring your cards or your phone if you want to buy anything.
The Forerunner 255 adds Garmin Pay for contactless payments. I can just tap the watch at a terminal, same as a contactless card.
Setting up Garmin Pay means adding your bank card through the Garmin Connect app. Not every UK bank is on board yet, but big names like Barclays and Santander work fine.
Garmin Pay benefits:
- No phone needed for small purchases
- Works at most contactless terminals
- Secured with a PIN code
- Perfect for post-run coffee stops
Payments have worked well for me. It’s surprisingly handy when you want to grab a snack or a drink after a run and don’t want to mess with cash or cards.
Battery Life and Real-World Performance
The Forerunner 55 gives you up to two weeks of battery life in smartwatch mode. The 255 manages 14 days for the regular size, and the smaller 255s gets 12 days because of its higher-res display.
Battery Longevity
Honestly, the Forerunner 55 is a bit of a champ with its two-week battery. It actually outlasts the regular Forerunner 255, which is still solid at 14 days.
The smaller Forerunner 255s drops to 12 days, mostly because that sharper screen uses up more juice.
When it comes to GPS tracking, both watches are about the same. I usually get somewhere between 15 and 20 hours of continuous GPS before needing a charge.
The 255 does burn through battery a bit faster if you’re using music or its extra features a lot. Still, I wouldn’t say it’s a deal breaker for most runners out there.
Charging and Usage Experience
Both watches use Garmin’s proprietary charging cable. It connects magnetically to the back, and honestly, I’ve never had it fall off or disconnect by accident.
Charging time? Pretty much the same for both models. From totally dead to full, you’re looking at about 1-2 hours.
I’ve noticed the 255’s battery indicator is just a bit more trustworthy than the 55’s. The 255 even gives you clearer heads-up warnings when you’re running out of juice.
How often you charge really depends on your habits. If you’re always using GPS or getting tons of notifications, expect to top up both watches about once a week instead of every two.
