You can combine most bands with any Apple Watch Series 3 or newer case of the same size. For Apple Watch Series 3, the 40mm band works with the 38mm case; the 44mm band works with the 42mm case. Apple Watch Series 4, Series 5 and Series 6 come in 40mm and 44mm case sizes, so they are the same. As long as you get the same size for the new Apple Watch, the existing bands should fit seamlessly.
The Apple Watch Series 7 was one of many announcements made during Apple's “California Streaming” event, sharing the stage alongside iPhone 13 and 13 Pro, a new iPad Mini with USB-C charging, and more. Apple Watch band sizes match the size of each device to ensure a comfortable fit and proper use. Made of leather, the modern buckle is the only Apple band that is exclusive to the smaller Apple Watch models of 40 and 41 mm. While you can't beat the quality of the original Apple Watch straps, you can also buy more exclusive designs on Etsy or Amazon at affordable prices.
For this band, Apple says the size starts at 130mm, but there is some margin here due to the tight fit, so it's also a good choice for smaller wrists. This is because when Apple slightly increased the size of the Apple Watch case, they kept the same strap sizes. As long as you take off and put on your Apple Watch bands properly, there shouldn't be any wear and tear associated with changing them. The quickest way to find out what size Apple Watch you have is to take the watch off your wrist and look at the engraving on the back.
For the most part, each Apple Watch band has a good size range, and you just need to pay close attention to whether your wrist is smaller than average or larger than average. However, if you use third-party Apple Watch bands, the band may wear out over time. 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. You don't need to be so careful with the other Apple Watch bands, but it's helpful to get accurate measurements to ensure a good fit.
These lengths can be added to the size of the Apple Watch to approximately equal the circumference of the wrist, plus or minus a few millimeters. Apple's printed guide provides a comparison of the size of the Apple Watch on the wrists for a powerful visual reference. The Modern Buckle is another strap that focuses more on fashion than functionality, and it's not designed to get wet.