Will My Old Apple Watch Straps Fit the Series 12?

Short answer: almost certainly, yes. The Apple Watch Series 12 comes in 42mm and 46mm, exactly the same sizes as the Series 10 and 11. Any strap that fits a Series 10 or 11 of the same size will fit a Series 12, and so will most straps from older watches in the same size family. If you've been building a little collection of straps, it moves to the new watch with you. (If you're starting from scratch, our Series 12 strap collection has everything that fits.)

There's one catch, and it trips up a lot of people. It's the number 42. Here's how to avoid it.

The two strap families (and why the size on the box isn't the whole story)

Every Apple Watch strap belongs to one of two families. Within a family, straps swap freely between cases.

• The small family: 38mm, 40mm and 41mm cases, plus the newer 42mm (Series 10, 11 and 12).
• The large family: the older 42mm (Series 1 to 3), plus 44mm, 45mm and 46mm, and the 49mm Ultra.

So for the Series 12:

• 42mm Series 12: straps from a 38mm, 40mm, 41mm, or Series 10/11 42mm watch will fit.
• 46mm Series 12: straps from a 44mm, 45mm, 46mm, 49mm, or old Series 1-3 42mm watch will fit.

If you want every Series and case size in one table, our Apple Watch strap size chart has the full breakdown. I won't repeat it all here.

The "42mm" catch

"Will this fit my watch?" is the question customers ask me most, and this is the version of it that trips people up. So it gets its own section.

For the first few years of the Apple Watch, 42mm was the big one. A Series 1, 2 or 3 in 42mm used large-family straps. In 2024 Apple brought the number back for the Series 10, but this time 42mm was the small size. The Series 11 and now the Series 12 have kept it.

That means two straps can both say "42mm" and fit completely different watches.

Your strap says 42mm, and it came from…	It fits the…
A Series 1, 2 or 3	46mm Series 12 (large family)
A Series 10 or 11	42mm Series 12 (small family)

If you've just upgraded from a very old 42mm Series 3 to a small 42mm Series 12, your old straps won't fit, even though the number matches. If you've gone from that same Series 3 to a 46mm Series 12, they will.

When you're buying new, ignore the millimetre label on its own and check which Series the product listing says it fits. On our listings the small family is labelled with the newer 42mm (Series 10 and 11), so you can see at a glance which size you need.

How to check which watch (and which straps) you've got

If you're not sure what your old watch was, you don't need the box.

• Turn the watch over. The case size is engraved on the back, next to the sensor. It'll say something like "41mm" or "44mm".
• Or check the iPhone. Open the Watch app, then General, then About. It shows the model name and case size.
• Straps with no label: measure the width where the strap slides into the watch. Put it next to a strap you know fits your new watch. If the connectors are the same width, it'll fit.

Still not sure? Take a photo of the back of your watch and email it over to me through our contact page. I'll tell you which straps fit. I personally answer these emails myself.

Which straps carry over, and which need a second look

The connector (the bit that slides into the watch) has stayed the same design since the very first Apple Watch, so any strap in the right size family clicks into a Series 12. The strap type matters a bit, though.

• Silicone and sport straps: carry over with no problems. If it fitted your old watch's size family, it fits.
• Braided elastic and stretch loops: these are sized to your wrist, not just the case. If your wrist hasn't changed, they'll fit exactly as before. If you've gone from a 41mm to a 46mm, you've also changed family, so you'll need new ones.
• Leather and buckle straps: carry over within the family. On a bigger case they can look a touch narrow at the join. That's a matter of taste, not fit.
• Milanese mesh and magnetic straps: carry over within the family. It's worth checking the magnet still holds firmly after a year or two of wear, but that's about the strap's age, not the new watch.
• Link bracelets: carry over, but if you had links removed for your wrist, you'll want to keep those spares.

Is it worth buying new straps for a new Apple Watch?

Honestly? Not unless you want to. The whole point of the Apple Watch's strap system is that the strap is the part you change, and the watch stays the same. Upgrading the watch shouldn't mean starting your collection again.

What a new watch is good for is filling the gaps. Most people's strap drawer has one sporty strap and one "going out" strap, with nothing in between. Around a fifth to a quarter of our customers come back for another strap, and it's highest among Apple Watch owners. That second or third strap is usually the one that gets the most wear: something for the office, the gym, or a colour that goes with the coat you actually wear.

A few that customers keep coming back for, all in the Series 12 collection:

• Braided Elastic, £16.99. Our bestselling Apple Watch strap by a distance, rated 4.7 from around 250 reviews. It comes in over a dozen colours, so it's the easiest way to build a rotation.
• Classic Silicone, £14.99. The everyday gym strap, and our cheapest way into the range.
• Alpine Style Summit Series Loop, £21.99. A tougher outdoor look, rated 4.8.
• Milanese Mesh, £21.99. The one that makes it look least like a gadget.
• Genuine Leather, £21.99. For when the watch needs to go to a meeting.

Every order ships free across the UK and comes with 60-day returns. Mixing and matching also gets cheaper the more you buy: 10% off two straps, 15% off three, and 20% off four or more.

Quick answers

Will my Series 11 straps fit the Series 12? Yes, as long as the size matches. A 42mm Series 11 strap fits a 42mm Series 12, and a 46mm fits a 46mm.

Will my Series 10 straps fit the Series 12? Yes, the same way. The Series 10, 11 and 12 all use 42mm and 46mm cases.

Will my old Series 3 strap fit the Series 12? A 38mm Series 3 strap fits the 42mm Series 12. A 42mm Series 3 strap fits the 46mm Series 12, not the 42mm one.

Will a 44mm or 45mm strap fit the 46mm Series 12? Yes. They're all in the large family.

Will Apple Watch Ultra straps fit the Series 12? 49mm Ultra straps fit the 46mm Series 12. They won't fit the 42mm.

Do I need a tool to swap them? No. Press the small button on the back of the watch, slide the old strap out sideways, and slide the new one in until it clicks. Easy!

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If you've got a drawer of straps from older watches and no idea what fits, send me a photo of the back of your old watch and I'll sort it out. And if you're starting fresh, the full Series 12 range is here.