Apple has used eight case sizes over the years, but they all fit into three Apple Watch connector groups: Small, Large, or Ultra. This Apple Watch band size guide will show you exactly how to find your watch model and your strap size in minutes.
Which Apple Watch do I have?
Every Apple Watch has a model number that begins with the letter “A” followed by four digits (for example, A2978).
The most reliable way to find it:
- Open the Apple Watch app on your iPhone
- Tap the My Watch tab
- Tap General, then About
- Find the Model field (it may first show a part number beginning with “M”)
- Tap the Model field once, it switches to the model number that begins with “A”
You can also open Settings > General > About on the watch itself and tap the Model field the same way.
On older models (Series 3 and earlier) the number is also engraved on the back of the case; on Series 4 and later it’s easiest to read from the app or Settings as above.
How Apple Watch Band Sizing Works
Unlike traditional watches, Apple Watch bands aren’t measured by lug width in millimeters. Instead, your case size decides which of three band groups you need. Any band built for one case in a group fits every other case in that group:
- Small connector group: fits 38mm, 40mm, 41mm, and the new 42mm on Series 10 and 11.
- Large connector group: fits the original 42mm from 1st gen to Series 3, plus 44mm, 45mm, and 46mm on Series 10 and 11.
- Ultra connector group: fits the 49mm Ultra. It shares the Large connector, so an Ultra band fits Large watches too, and a Large band fits the Ultra for casual wear.
Once you know your size, you can wear any strap that fits it.
Exception: Apple Watch Series 1/2/3
The early Apple Watches, from the original through Series 3, feature 38mm and 42mm cases, and those numbers don’t match the size options you’ll pick today.
- If your case reads 38mm it will fit our Small size, choose the 40mm, 41mm, and 42mm.
- If your case reads 42mm it will fit our Large size, choose the 44mm, 45mm, 46mm, and 49mm option.
Please note: Even though 42mm also appears in the Small option, the original 42mm case size is a Large-connector watch, so it needs the Large size.
Apple Watch Size Comparison Chart
Each device is listed once per case size, and the model numbers cover GPS, GPS + Cellular, and the main regional variants, including China mainland. If your model number isn’t listed in this Apple Watch band size guide, you can match by case size instead or contact us for further assistance.
| Model number(s) | Device | Size to select |
|---|---|---|
| A3331, A3450, A3335, A3452 | Apple Watch Series 11, 42mm | 40/41/42mm, Small |
| A3333, A3451, A3337, A3453 | Apple Watch Series 11, 46mm | 44/45/46/49mm, Large |
| A3324, A3391, A3326, A3327 | Apple Watch SE 3, 40mm | 40/41/42mm, Small |
| A3325, A3392, A3328, A3329 | Apple Watch SE 3, 44mm | 44/45/46/49mm, Large |
| A3281, A3282 | Apple Watch Ultra 3, 49mm | 49mm, Ultra |
| A2997, A2998, A3001, A3002 | Apple Watch Series 10, 42mm | 40/41/42mm, Small |
| A2999, A3000, A3003, A3206 | Apple Watch Series 10, 46mm | 44/45/46/49mm, Large |
| A2986, A2987 | Apple Watch Ultra 2, 49mm | 49mm, Ultra |
| A2978, A2982, A2983 | Apple Watch Series 9, 41mm | 40/41/42mm, Small |
| A2980, A2984, A2985 | Apple Watch Series 9, 45mm | 44/45/46/49mm, Large |
| A2622, A2684, A2859 | Apple Watch Ultra, 49mm | 49mm, Ultra |
| A2770, A2772, A2773, A2857 | Apple Watch Series 8, 41mm | 40/41/42mm, Small |
| A2771, A2774, A2775, A2858 | Apple Watch Series 8, 45mm | 44/45/46/49mm, Large |
| A2722, A2725, A2726, A2855 | Apple Watch SE 2nd gen, 40mm | 40/41/42mm, Small |
| A2723, A2724, A2727, A2856 | Apple Watch SE 2nd gen, 44mm | 44/45/46/49mm, Large |
| A2473, A2475, A2476 | Apple Watch Series 7, 41mm | 40/41/42mm, Small |
| A2474, A2477, A2478 | Apple Watch Series 7, 45mm | 44/45/46/49mm, Large |
| A2291, A2293, A2375 | Apple Watch Series 6, 40mm | 40/41/42mm, Small |
| A2292, A2294, A2376 | Apple Watch Series 6, 44mm | 44/45/46/49mm, Large |
| A2351, A2353, A2355 | Apple Watch SE 1st gen, 40mm | 40/41/42mm, Small |
| A2352, A2354, A2356 | Apple Watch SE 1st gen, 44mm | 44/45/46/49mm, Large |
| A2092, A2094, A2156 | Apple Watch Series 5, 40mm | 40/41/42mm, Small |
| A2093, A2095, A2157 | Apple Watch Series 5, 44mm | 44/45/46/49mm, Large |
| A1977, A1975, A2007 | Apple Watch Series 4, 40mm | 40/41/42mm, Small |
| A1978, A1976, A2008 | Apple Watch Series 4, 44mm | 44/45/46/49mm, Large |
| A1858, A1860, A1889, A1890 | Apple Watch Series 3, 38mm | 40/41/42mm, Small |
| A1859, A1861, A1891, A1892 | Apple Watch Series 3, 42mm | 44/45/46/49mm, Large |
| A1757, A1816 | Apple Watch Series 2, 38mm | 40/41/42mm, Small |
| A1758, A1817 | Apple Watch Series 2, 42mm | 44/45/46/49mm, Large |
| A1802 | Apple Watch Series 1, 38mm | 40/41/42mm, Small |
| A1803 | Apple Watch Series 1, 42mm | 44/45/46/49mm, Large |
| A1553 | Apple Watch 1st gen, 38mm | 40/41/42mm, Small |
| A1554 | Apple Watch 1st gen, 42mm | 44/45/46/49mm, Large |
Choosing the Right Band Length
Once you know your Apple Watch band size, choose a length to match your wrist. The length options depend on the band style.
| Length Option | Approx. Total Strap Length |
|---|---|
| Short–Medium | 210mm–215mm |
| Medium–Long | 225mm–240mm |
| Adjustable or one-size | Adjusts or stretches 160mm–250mm to fit most wrists |
The lengths shown are the total strap length from each product page, not a wrist circumference. To measure your wrist, wrap a tape measure or a strip of paper against a ruler just below the wrist bone. Always check the product page for its exact measurements.