The bands for 38mm, 40mm and 41mm housings work with each other, and the bands for 42mm, 44mm and 45mm housings work with each other. Most bands designed for Apple Watch Series 4, Apple Watch Series 5, Apple Watch SE, Apple Watch Series 6 and Apple Watch Series 7 work with any previous version of Apple Watch. Of course, as always, you'll need the right strap size for the right watch size. Older bands that fit the 40mm Apple Watch Series 6 will fit Series 7, and the 44mm straps will fit the new 45mm size.
Remember that since all bands will be compatible with the new Apple Watch, there is no reason to wait for the launch of Apple Watch Series 7 to buy new bands if you are looking for a new look. We've combined the new 41mm Solo Loop in English Lavender with the 40mm Series 6 in aluminum (blue), as well as the new Nike Sport Loop 45mm in black with the Apple Watch SE 44mm in black aluminum. With the Apple Watch coming in so many different case sizes, it's no wonder people get confused as to which of the different watch bands will fit the watch they have. Weinbach's information that the new Apple Watch “will use different straps that won't be compatible with old watches is open to interpretation, at best.
At the same time, normal watch bands introduced after Series 4 are theoretically “designed for Series 4 and are compatible with previous generations. When you buy an Apple Watch band, you may need to specify which watch it is for, large or small, but you can usually get any of the bands for any of the watches. Getting a larger Apple Watch band basically ensures that it will work with previous wearables that were the larger size option of their respective generation. The watch comes in a new case size of 41 mm and 45 mm, moving away from the 40 mm and 44 mm size that has been the standard of the last generations of Apple Watch.
At this point, it's pretty certain that the Apple Watch Series 7 will have a completely new design with flat edges and new sizes. With the Apple Watch Series 4, the company rounded up the product a little more and increased the sizes to 40mm and 44mm. While I think the new straps will be labeled 41mm and 45mm, that doesn't mean they won't work with older watches. In case you didn't know, they're only compatible with Apple Watch SE, Series 4, and newer models.
Since the older Series 3 bands fit all Series 6 and SE, Apple Watch fans have plenty of straps. However, Max Weinbach has now said on Twitter that the new Apple Watch straps “will not be compatible with old watches. Luckily, Apple has stated that all of the above bands will work with the Apple Watch Series 7, so you don't need to replace all of your best Apple Watch bands if you plan to buy the newest Apple Watch.