Will my old straps fit the Apple Watch Series 12 and Ultra 4?
Yes, in most cases. Apple unveiled the Series 12 and Ultra 4 on 9 September, and sales began on 18 September. The Series 12 is available in 42mm and 46mm, just like the Series 10 and 11, and the Ultra 4 has the same 49mm case as the Ultra, Ultra 2 and Ultra 3. Apple Watch straps are categorised by case size, so the model year doesn’t matter, and most straps you already own will work with your new watch.
Where things can go wrong is with the 42mm size. It means different things across different generations, so a strap labelled 42mm won’t always fit the new watches. The table below shows exactly what fits.
How your old straps fit
Find the row for your current watch. The size is engraved on the back of the case, near the heart rate sensors.
| Your old watch | Series 12 (42mm) | Series 12 (46mm) | Ultra 4 (49mm) |
| Series 1-3, 38mm | Yes | No | No |
| Series 1-3, 42mm | No | Yes | Yes |
| Series 4-6 and SE, 40mm | Yes | No | No |
| Series 4-6, and SE, 44mm | No | Yes | Yes |
| Series 7-9, 41mm | Yes | No | No |
| Series 7-9, 45mm | No | Yes | Yes |
| Series 10-11, 42mm | Yes | No | No |
| Series 10-11, 46mm | No | Yes | Yes |
| Ultra, Ultra 2, Ultra 3 (49mm) | No | Yes | Yes |
Please note that Apple recommends standard 44, 45 and 46mm straps on an Ultra for everyday use only. More on this under Ultra 4 below.
Why Series 12 follows Series 10 and 11
Apple itself specifies compatibility based on case size, not on watch model (Apple’s support page). The straps are divided into two groups with different lug widths:
- Smaller group: 38, 40, 41 and the new 42mm
- Larger group: the old 42mm, 44, 45, 46 and 49mm
The Series 12 has the same sizes as the Series 10 and 11 and therefore falls into the same groups. The old 42mm case on Series 1–3 was the larger size, whilst the 42mm on Series 10–12 is the smaller one. Consequently, a strap labelled 42mm may belong to either group. We explain the difference in Apple Watch 42mm: two watches, different straps.
The full line-up for Apple and all other brands can be found in our compatibility guide.
Apple Watch Ultra 4
The Ultra 4 retains the 49mm case and shares straps with all previous Ultra models. Straps from an Ultra 3 will therefore fit without any modifications.
The Ultra also accepts straps for 44, 45 and 46mm models, and 49mm straps fit the larger cases, including the Series 12 46mm. The Ocean Band, Alpine Loop and Trail Loop, however, are designed for the Ultra’s larger case and for rugged use such as hiking, climbing and diving. Apple states that 44, 45 and 46mm straps on an Ultra should only be used for everyday wear. If you use the watch for exercise and adventure, a 49mm strap is the right choice.
Ceramic Series 12
The Series 12 is also available in ceramic. Apple’s specifications list the ceramic cases as 43 and 47mm – one millimetre larger than the aluminium and titanium models – but the straps are still labelled 42 and 46mm. Choose a strap from the smaller range (38/40/41/42mm) for the 43mm model, and a strap for the larger range (44/45/46/49mm) for the 47mm model.
Do you need to buy a new strap?
The straps for the Series 12 and Ultra 4 are the same as for the previous generation, so you’ll find the right selection here:
- For the Series 12 42mm: the straps from the Apple Watch Series 11 42mm
- For the Series 12 46mm: the straps from the Apple Watch Series 11 46mm
- For the Ultra 4: the straps from the Apple Watch Ultra 3, or the entire Ultra range
Frequently asked questions
Do Series 11 straps fit the Series 12?
Yes. The Series 12 has the same 42mm and 46mm sizes as the Series 11 and follows the same compatibility groups. Straps for the 42mm model fit the 42mm model, and straps for the 46mm model fit the 46mm model.
Do Ultra 3 straps fit the Ultra 4?
Yes. The Ultra 4 has the same 49mm case as the Ultra, Ultra 2 and Ultra 3, and all four share the same straps.
Do Ultra straps fit the Series 12?
On the 46mm model, yes. 49mm straps fit all watches in the larger group. On the 42mm model, they do not fit, as it belongs to the smaller group.
Can I use Series 12 straps on the Ultra 4?
Yes, straps for the 44, 45 and 46mm models fit the Ultra 4. However, Apple only recommends them for everyday use. For heavy-duty use, Ultra straps are better.
Do my old 42mm straps from Series 1–3 fit the Series 12?
On the 46mm model, yes. On the 42mm model, no. The old 42mm case belongs to the larger group and therefore has the same attachment as the 44, 45 and 46mm models.
Which straps fit the ceramic Series 12?
The ceramic models are listed as 43 and 47mm, but the straps are marked 42 and 46mm. The 43mm model takes straps for 38/40/41/42mm, and the 47mm model takes straps for 44/45/46/49mm.
