Garmin Forerunner Band Size: What Actually Fits Your Watch
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Your Garmin Forerunner band size depends on the model, not the brand. The 265 and 255 take 22mm, the 265S and 255S take 18mm, and the 165, 55, 245 and 645 take 20mm. The 570 splits by case size: the 42mm takes 20mm and the 47mm takes 22mm. Every model in the table below uses standard quick-release spring bars, so a normal watch strap fits straight on. There's no adapter, no proprietary connector and no Garmin-only part.
That last bit surprises people. The stock band is moulded to the case and looks built in, so most owners assume they're locked into Garmin's own replacements. They aren't.
Forerunner sizes, model by model
Find your model, note the number, buy that size. Each model name links to its own page on the store, already filtered to the right width.
| Model | Band size |
|---|---|
| Forerunner 55 | 20mm |
| Forerunner 165 / 165 Music | 20mm |
| Forerunner 245 / 245 Music | 20mm |
| Forerunner 255 / 255 Music | 22mm |
| Forerunner 255S / 255S Music | 18mm |
| Forerunner 265 | 22mm |
| Forerunner 265S | 18mm |
| Forerunner 570, 42mm case | 20mm |
| Forerunner 570, 47mm case | 22mm |
| Forerunner 645 / 645 Music | 20mm |
There are three traps in that table.
The S isn't a trim level. It's a smaller case with narrower lugs. A 265S takes 18mm, not 22mm. If you own an S model and order the size your mate with the standard model uses, it won't go on.
The Music version is the same watch physically. A 255 Music takes exactly what a 255 takes, because the audio storage doesn't change the lugs.
The 570 comes in two case sizes and they take different straps. Check the case size on the box or the caseback before you order.
Not sure which model you own?
There are two ways to check, and both take under a minute.
Read the watch. Flip it over. The model name is printed on the caseback, usually under the sensor. On a 265S it says 265S, not 265.
Measure the gap. Pull the old band off and put a ruler across the space between the two lugs, which are the metal ears the band sits between. Measure the gap itself, not the case and not the band. You'll land on 18, 20 or 22. Round to the nearest even number, because watch lugs come in even sizes. There's a longer walkthrough in our post on how to measure the lug width of your watch.
If the gap measures 21.4, it's a 22. Rulers and lug edges aren't precise enough to give you an odd number.
Do you need a spring bar tool?
No. Every strap we sell ships with quick-release spring bars, which are spring bars with a small lever built into the shaft. You slide the lever with a fingernail, the bar retracts and the strap comes off. Fitting the new one is the same move in reverse.
That matters more on a running watch than on anything else, because you actually swap it. You can wear a sweaty band for the long run and a dry one to the office, and the change takes thirty seconds on the kitchen bench with no bench block and no scratched lugs.
We do sell a spring bar tool for $14 if you own other watches with standard bars. For a Forerunner and one of our straps, you won't need it.
Which strap suits a running watch?
Match the material to what you do in it, not to what looks good in a photo.
- FKM rubber. This is the default for a Forerunner. It shrugs off sweat, sunscreen and chlorine, it doesn't hold smell, and it wipes clean under a tap. Our FKM rubber straps are $54.
- Sailcloth over rubber. You get fabric texture on top and rubber against the skin, so it looks less like gym kit and wears like rubber.
- Seatbelt NATO. It's nylon in one continuous piece under the caseback, so the watch can't fall off if one spring bar lets go. It dries fast and it's cheap to swap colours. Ours come in 20mm and 22mm, so it's not an option for the S models.
- Leather. This is the wrong call for a running watch. Sweat and repeated wetting ruin leather quickly, and a Forerunner spends its life getting wet. Save it for a watch you wear to dinner.
For a 22mm Forerunner, The Bastion in black is the boring correct answer. It's matte and dark, it disappears against the case, and it takes a beating without looking like it.
Go straight to your size
Every model in the table links to its own page. If you'd rather browse by width, these three pages hold everything we make in each size.
- 18mm watch straps for the 265S and 255S
- 20mm watch straps for the 55, 165, 245, 645 and the 42mm 570
- 22mm watch straps for the 265, 255 and the 47mm 570
The buying details
- Shipping is free on orders over $64.
- You've got 30 days to change your mind. Return postage is on you.
- There's a 1 year warranty against manufacturing defects.
- Every strap comes with quick-release spring bars.
Get the size right, then pick a colour
The hard part of buying a Forerunner strap is one number. Get 18, 20 or 22 right and the rest is taste.
Check your caseback, find your model in the table above and open the page for it. If you're still unsure after measuring, send us the model name and we'll tell you which one to order.