The sizes of the Apple Watch 7 are a bit confusing. For the first time, it is available in 41mm and 45mm models.

This is the second time Apple has resized its smartwatches; the Apple Watch 4 added 40mm and 44mm, up from 38mm and 42mm in the Apple Watch 3. And now the Apple Watch 7 is positioned to be the best Apple Watch yet for users craving larger wrist candy.

Apple's only mention of Apple Watch size changes was in reference to watch band compatibility. The company has promised that all existing Apple Watch bands will work with the Series 7 and its expanded display, and if you have accumulated a collection of cool straps, it won't be worthless if you decide to upgrade if you decide to upgrade.

Now that the Apple Watch 7 is here, there are some things you should know about the new Apple Watch 7 sizes.

The Apple Watch 7 comes in 45mm and 41mm sizes. The case growth is barely noticeable, though enough to justify changing the 44mm and 40mm sizes from the previous model.

If you purchase an Apple Watch band today, you can choose between 41mm and 45mm case sizes for compatibility. The company advises that 41mm straps are compatible with 38mm and 40mm cases, while 45mm straps are compatible with 42m and 44mm cases. In other words, the new bands are compatible with Apple Watch Series 3 and later (including the mid-range Apple Watch SE). There appears to be some commonality in the compatibility of the straps and watchOS 8.

Whether you are buying a new band for your current Apple Watch or want to know what will happen to your current band when you buy a new Apple Watch, you will need to do some research.

Before you buy a new band for your Apple Watch 6, Apple Watch 5, or any other Apple Watch model, take note of the size of your smartwatch. The size is listed on the back of the smartwatch.

If your Apple Watch is 38 mm or 40 mm, purchase a 41 mm band; if your Apple Watch is 42 mm or 44 mm, purchase a 45 mm band. This tip does not apply to Apple Watch Series 2 and earlier.

If you are planning to purchase an Apple Watch 7 or want to purchase a pair of straps for someone who is planning to purchase an Apple Watch 7, the strap size options will match the Apple Watch 7 case size options. You may also want to choose the size of your new Apple Watch based on the band you already have.