If you are upgrading from an older Galaxy Watch, the first question is whether your band collection comes with you. As of the Watch 8, the answer changed.
The short version
There are now three separate groups, and bands do not cross between them.
Dynamic Lug (Watch 8, Watch 8 Classic, Watch 9): Samsung's proprietary slide-in connector. No standard band fits, and no older Galaxy Watch band fits.
Dynamic Lug, Ultra width (Galaxy Watch Ultra): the same style of connector but wider, so Ultra bands and Watch 8 bands are not interchangeable.
Standard spring bars (Watch 7 and earlier): 20mm on the Watch 4 through 7, 22mm on the older and larger models.
The 20mm group
Galaxy Watch 4, 5, 6 and 7, in both standard and Classic versions and every case size, all take 20mm quick-release bands. So does the Watch FE.
Within this group everything is interchangeable. A band bought for a Watch 5 fits a Watch 7, and a band bought for a Watch 6 Classic fits a Watch 4.
Case size does not determine band size. A 47mm Watch 6 Classic and a 40mm Watch 5 both take 20mm, because the lugs sit the same distance apart.
The 22mm group
Galaxy Watch 3 45mm, the original Galaxy Watch 46mm, and the Gear S3 Frontier and Classic.
Moving from one of these to anything recent means starting over, and there is no adapter worth using between 20mm and 22mm lugs.
Upgrading to a Watch 8: what to expect
This is the break worth planning for. Bands from the Watch 4, 5, 6 and 7 will not fit a Watch 8 or Watch 8 Classic, and neither will any generic 20mm strap.
Watch 8 bands come in two sizes: small for the 40mm Watch 8, large for the 44mm Watch 8 and the 46mm Watch 8 Classic.
Dynamic Lug adapters exist that accept a conventional pin-style band. They work, but they add bulk at the lug, can affect how the case sits against the wrist, and rarely look as clean as a purpose-made band. Useful as a stopgap for straps you love; not a long-term answer.
What about the Galaxy Watch FE?
The FE follows the 20mm standard of the Watch 4 to 7 generation rather than the Watch 8's connector.
How to check yours in ten seconds
Look at where the band meets the case. If you can see a spring bar with a small sliding lever, you have a standard fitting and you need a lug width. Measure the gap between the lugs, not the band itself, since bands are usually cut slightly narrower.
If there is no visible pin and the band slides into the case, you have a Dynamic Lug model and you shop by watch name instead.
One more thing on the spring-bar models
Getting the width right means the band fits. It does not mean it looks right. A straight-ended band meets a round case at a single point and leaves a small gap at each side. No-gap bands are shaped to follow the curve.
Shop Samsung Galaxy Watch bands, or read our Galaxy Watch 8 guide.
