Which Apple Watch Strap Fits Your Watch? The Size Groups, What 42mm Means, and How to Change One
Apple Watch straps come in two fitting groups. Straps made for 38mm, 40mm and 41mm cases swap between each other, and straps made for 44mm, 45mm, 46mm and 49mm cases swap between each other. The catch is 42mm, which has meant two different things: on a Series 1, 2 or 3 it was the big case, and on a Series 10 or 11 it is the smaller of the two. Check which watch you have before you check the number on the strap.
What brought you here?
- Will this strap fit my watchTwo groups, and one number that means two things. The fitting rules
- What size is my watchEvery model and its case size. Find your watch
- How do I get the old one offThere is a button, and it needs holding. Changing a strap
- It will not slide outAlmost always the same two mistakes. When it sticks
- Which strap is comfortableSport Band, Sport Loop and the Nike versions. The everyday ones
- I want metalMilanese, Link Bracelet and the gold question. Metal straps
- Will it fit my wristApple publishes the millimetres. Wrist sizes
- Why are they so expensiveApple charges £49 to £899. Where the money goes
We sell Apple Watch straps, so to be clear about what this page is: every size, rule and measurement below was read on Apple's own support and store pages this week and is listed at the bottom with links. There are no prices from our shop in the writing, and the only products appear in one block at the end, after the advice.
- Which Apple Watch strap fits your watch
- Apple Watch strap sizes: 38, 40, 41, 42, 44, 45, 46 and 49mm
- Apple Watch straps by model: Series 3, SE, Series 11 and Ultra
- How to change an Apple Watch strap
- How to remove an Apple Watch strap that will not come off
- Sport Band, Sport Loop and the Nike straps
- Metal, steel, silver and gold Apple Watch straps
- Apple Watch straps for women and men, and what wrist size means
- Why Apple Watch straps cost £49 to £899
- Which Apple Watch strap should you buy
- Quick answers
You have found a strap you like, and now you are staring at a list of numbers trying to work out whether it fits the watch on your wrist. It is a fair thing to be stuck on. Apple has used eight different case sizes since 2015, changed which numbers count as small and large partway through, and its own support page still describes the older arrangement.
This page sorts it out. The fitting rules come from Apple, the case sizes come from Apple’s own model list, and the wrist measurements come from Apple’s product pages. Where Apple contradicts itself, which it does on one point, that is flagged rather than smoothed over.
Which Apple Watch strap fits your watch
Apple’s rule is simpler than the number of sizes suggests. Straps are not tied to a specific model. They are tied to a lug width, and the case sizes fall into two groups that share one. In Apple’s words, you can use a strap designed for other Apple Watch models as long as the sizes are compatible.
The two groups are:
- The small group: straps for 38mm, 40mm and 41mm cases are compatible with each other.
- The large group: straps for 44mm, 45mm and 46mm cases are compatible with each other, and with 49mm cases. Straps sold as 49mm also fit 44mm, 45mm and 46mm. Apple also groups the old 42mm here, so a strap from a Series 1, 2 or 3 fits a 44mm or 45mm watch.
So a Sport Band bought for a 45mm Series 9 goes straight onto a 46mm Series 11, and a Sport Loop from a 40mm SE fits a 41mm Series 9. You are matching the group, not the model. That is worth knowing if you are hunting for a strap for Apple Watch models Apple no longer sells, because plenty of older stock still fits a current watch.
There is one exception worth knowing before you buy. Apple says the Ultra is compatible with 44mm, 45mm and 46mm straps, but that those strap sizes should only be worn for casual, everyday use. The Ocean Band, Alpine Loop and Trail Loop are 49mm straps built for rugged activity, and they are the ones Apple intends you to wear for hiking, climbing or diving. A normal Sport Band on an Ultra is fine for the office. It is not what Apple recommends for the water.
Apple Watch strap sizes: 38, 40, 41, 42, 44, 45, 46 and 49mm
Here is every size Apple has used, and what it swaps with.
| Strap size | Also fits | Group |
|---|---|---|
| 38mm | 40mm, 41mm | Small |
| 40mm | 38mm, 41mm | Small |
| 41mm | 38mm, 40mm | Small |
| 42mm (Series 1 to 3) | 44mm, 45mm | Large, older naming |
| 42mm (Series 10 and 11) | 38mm, 40mm, 41mm | Small, current naming |
| 44mm | 42mm (Series 1 to 3), 45mm, 46mm, 49mm | Large |
| 45mm | 42mm (Series 1 to 3), 44mm, 46mm, 49mm | Large |
| 46mm | 44mm, 45mm, 49mm | Large |
| 49mm | 44mm, 45mm, 46mm | Large |
The 42mm row is the one that catches people out, and it is worth slowing down on. When Apple launched the Watch in 2015 the two sizes were 38mm and 42mm, so 42mm meant the larger watch. Apple’s support page still lists 42mm alongside 44mm and 45mm for that reason. But the Series 10 and Series 11 come in 42mm and 46mm, and here 42mm is the smaller of the two. Apple’s current 46mm Sport Band lists its compatibility as 44mm, 45mm, 46mm and 49mm, with no 42mm in sight.
What that means for you: if you own a Series 10 or Series 11 in 42mm, buy straps described as 38mm, 40mm, 41mm or 42mm for the current generation, and treat any 42mm strap listed next to 44mm and 45mm as a strap for an old Series 3. If a listing gives a range such as 42/44/45/49mm, that is the large group.
One caveat on the table above. Apple states the group rules and it states the case size of every model, but it has not published a line saying the current 42mm sits with 38mm, 40mm and 41mm. That row is our reading of Apple’s own pages, based on the 42mm being the smaller of the two current sizes and on the current 46mm Sport Band listing its fit as 44mm, 45mm, 46mm and 49mm with no 42mm among them. If you are ordering for a Series 10 or 11 in 42mm and the listing is vague, check the seller’s stated fit before you buy.
Apple Watch straps by model: Series 3, SE, Series 11 and Ultra
If you are not sure what size case you have, flip the watch over. The case size is engraved on the back. Failing that, this is Apple’s own list for the models still in circulation.
| Watch | Case sizes | Buy straps from |
|---|---|---|
| Apple Watch Series 11 | 42mm / 46mm | Small group for 42mm, large group for 46mm |
| Apple Watch SE 3 | 40mm / 44mm | Small group for 40mm, large group for 44mm |
| Apple Watch Ultra 3 | 49mm | Large group, 49mm straps for anything rugged |
| Apple Watch Series 10 | 42mm / 46mm | Small group for 42mm, large group for 46mm |
| Apple Watch Ultra 2 | 49mm | Large group, 49mm straps for anything rugged |
| Apple Watch Series 9 | 41mm / 45mm | Small group for 41mm, large group for 45mm |
| Apple Watch Series 8 | 41mm / 45mm | Small group for 41mm, large group for 45mm |
| Apple Watch SE (2nd generation) | 40mm / 44mm | Small group for 40mm, large group for 44mm |
If you are still deciding which watch to buy rather than which strap to put on it, our smartwatch buying guide covers the models themselves.
If you have a Series 3, you are on the old naming. The 38mm takes small group straps and the 42mm takes large group straps, which is the reverse of what a Series 11 owner would expect from the same number.
If you have an Ultra or Ultra 2, the 49mm straps are the ones designed for it. Every Apple Watch Ultra strap Apple builds for rough use is a 49mm one. There is one more wrinkle Apple mentions: if you like the Solo Loop or Braided Solo Loop, you may need a smaller size than you are used to, because the Ultra case is larger. Apple’s advice is to try the strap with the watch before buying, which is sensible given those two are sized to your wrist rather than adjustable.
How to change an Apple Watch strap
It takes about ten seconds once you know where the button is, and the first time nearly always takes longer than that. How to change Apple Watch strap fittings, in Apple’s own steps:
- Put the watch face down on something soft. A microfibre cloth or a padded mat. The back of an Apple Watch scratches.
- If you are removing a Link Bracelet, press the quick release button on one of the links and separate the bracelet into two pieces first. Taking it off in one piece puts strain on the lugs.
- Find the strap release button. It sits on the back of the case, just above and below where the strap enters. There are two, one per strap half.
- Hold the button down and slide the strap sideways, out of the channel. Sideways, not down or out.
- To fit the new one, make sure the text on the strap faces you, then slide it in until you feel and hear a click.
That click matters. If you did not hear it, the strap is not seated, and it will come off your wrist at some point when you would rather it did not. Give it a firm tug before you wear it.
How to remove an Apple Watch strap that will not come off
Most people looking up how to remove Apple Watch strap halves are not dealing with a broken watch. If the strap will not slide, it is almost never seized. Apple’s own instruction covers the usual cause: press the strap release button again, and make sure you hold it down. People press it like a doorbell and then pull. The button has to stay in while the strap moves.
The other two causes, in order of how often they happen:
- You are pulling in the wrong direction. The strap slides across the case, not away from it. Push it sideways with your thumb rather than pulling it outwards.
- It is a Link Bracelet still in one piece. Separate it at a link first, as above. Apple is explicit that you should not force it.
One more, for the metal straps: the Milanese Loop was redesigned in 2018 so the magnetic closure can slide all the way through the lug. On a Milanese Loop older than that, the closure will not pass through, and trying to force it is how the mesh gets bent. If your Milanese predates 2018, unfasten it rather than sliding it.
Sport Band, Sport Loop and the Nike straps
These three are what most people wear most days, and they are genuinely different rather than the same strap in different colours.
- Sport Band. Fluoroelastomer, which is a soft rubber. It has a pin and tuck fastening. It is the one to have if you sweat in it or get it wet, because it wipes clean and does not hold water. It can feel slightly clammy on a hot day.
- Sport Loop. Woven nylon with a hook and loop fastener. It breathes, it adjusts to any point rather than to fixed holes, and it is the more comfortable of the two for sleeping and for all day wear. It does absorb water, so it is the worse choice for swimming.
- Nike versions. The Nike Sport Band is the same fluoroelastomer with compression moulded perforations, which is the ventilation the standard Sport Band lacks. The Nike Sport Loop is the woven one in Nike colourways.
If you are buying one strap and want it to do everything, get a Sport Loop. If you swim or lift, get a Sport Band and accept that it is less pleasant in bed.
Metal, steel, silver and gold Apple Watch straps
Apple makes three metal straps, and they behave differently from each other.
- Milanese Loop. Stainless steel mesh with a magnetic closure that adjusts anywhere along its length, so it fits almost any wrist without tools. The easiest metal strap to live with.
- Titanium Milanese Loop. The same idea in titanium, lighter, and priced well above the steel one.
- Link Bracelet. Solid links with a butterfly closure. It is resized by removing links, which you do by hand with the quick release, no tools required. It is the dressiest and the heaviest.
On the gold question, which a lot of people search for: Apple sells its metal straps in finishes such as natural, slate, gold and black titanium rather than in solid gold. What you are buying is a coated or anodised finish, and that matters because finishes wear at the edges over years while the steel underneath does not. If you want gold on a watch you will wear daily, the Link Bracelet and Milanese in gold finish look the part; expect the high points to brighten with time.
A practical note before you commit to metal. All three are noticeably heavier than a Sport Band, and on a 49mm Ultra that difference is real on the wrist by the end of a day.
Apple Watch straps for women and men, and what wrist size means
Apple does not divide its straps by gender, and neither will this page, because the thing that actually decides fit is the number Apple prints on the box. Straps come in wrist size ranges, and those ranges are published.
For the current Sport Band, Apple lists:
| Strap size | Fits wrists |
|---|---|
| S/M | 140mm to 190mm |
| M/L | 160mm to 210mm |
| Extra Large | 195mm to 245mm |
Take a tape measure round your wrist bone before you order. It takes a moment and it removes the guesswork, particularly in the overlap between S/M and M/L where either would technically fit but one will sit better.
Searches for an Apple Watch strap women wear, or an Apple Watch strap men prefer, are usually really about two things: case size and strap width. A 41mm or 42mm watch on a slimmer wrist looks in proportion, a 46mm or 49mm does not, and the strap follows the case. If you are buying a strap as a gift and you do not know the watch, the case size engraved on the back is the thing to ask for.
Why Apple Watch straps cost £49 to £899
People ask this constantly, and the range is real. On Apple’s own UK store today, a Sport Loop is £49, an Alpine Loop, Trail Loop or Ocean Band is £99, a Modern Buckle is £149, a Titanium Milanese Loop is £199, and the Hermès straps run from £299 to £899 for the Satiné Grand H.
What you are paying for, in descending order of how much it actually affects you:
- Material and construction. Titanium and stainless steel cost more than woven nylon, and a Link Bracelet has dozens of machined parts where a Sport Loop has none.
- The lug. Every genuine strap has a moulded connector engineered to the case tolerance. This is the part cheap third party straps get wrong, and a loose lug is how a watch ends up on the pavement.
- Brand. The Hermès straps are a fashion product. There is nothing technically superior about a £899 strap over a £199 one.
Our recommendation: buy genuine for the strap you wear every day, because the lug is the part that fails and it is the part you cannot inspect in a photo. For an occasional colour change, third party is a reasonable risk. Do not spend Hermès money expecting Hermès durability, because those straps are leather and fabric that need the same care as any other.
Which Apple Watch strap should you buy
There is no single best Apple Watch band, because the right one depends on what your wrist is doing while you wear it. Working from the two things that actually decide it, your case size group and what you do while wearing it:
- One strap for everything: Sport Loop. Comfortable all day, adjusts anywhere, survives a workout.
- You swim or train hard: Sport Band, or the Nike Sport Band if you want the ventilation holes.
- You wear a shirt to work: Milanese Loop. It dresses up better than anything else Apple makes and adjusts without tools.
- You have an Ultra and you use it outdoors: Alpine Loop or Trail Loop for land, Ocean Band for water. These are the 49mm straps Apple designed for it.
- You want the dressiest thing available: Link Bracelet, and be ready for the weight.
- You are buying a second strap to swap colours: Sport Band. It is the cheapest genuine option and the easiest to clean.
Whatever you choose, check the group first. A strap you love in the wrong group is a strap you cannot wear. If you would rather browse the full range by family and size, they all sit in our smartwatch bands and straps section.
These are Apple straps we currently have, one from each family, so you can see the shapes side by side.
Apple Ocean Band Extension for Watch 44mm 45mm 46mm 49mm – Ice Blue Fluoroelastomer with Titanium Loop
In stock
Apple Modern Buckle Smartwatch Band 41mm Berry FineWoven Polyester for Apple Watch 135-150mm
In stock
Apple Magnetic Link Smartwatch Band for Watch 42mm, 44mm, 45mm, 49mm – Green S/M
In stock
Apple Watch Sport Loop Band for 38/40/41mm – Green
In stock
Apple Milanese Loop Stainless Steel Smartwatch Band M/L 44/45/46/49mm Slate
In stock
Quick answers
In fitting terms, yes. Apple says straps for 38mm, 40mm and 41mm cases are compatible with each other, so a 38mm or 41mm strap will fit a 40mm watch. What changes between them is the strap length and the wrist range, not whether the lug slots in.
Yes. The strap is designed to be removed by the owner, with no tools. Hold the strap release button on the back of the case and slide the strap sideways out of its channel. Any strap from the same fitting group will go in its place.
On the back of the case, at the top and bottom of the channel the strap slides into. There is one for each strap half. It sits almost flush, so it is easier to find by feel than by looking.
Two. Hold the release button down for the whole movement rather than pressing and releasing it, and push the strap sideways across the case rather than pulling it away. If it is a Link Bracelet, separate it into two pieces at a link before you try to remove it.
Turn the watch over. The case size is engraved on the back. Then match the group: 38mm, 40mm and 41mm swap with each other, and 44mm, 45mm, 46mm and 49mm swap with each other. For strap length, Apple publishes wrist ranges, with S/M covering 140mm to 190mm wrists and M/L covering 160mm to 210mm.
Both, and it is a wrist size question rather than a gender one. The 42mm is the smaller of the two current sizes on a Series 10 or 11, and the 46mm is the larger. Measure your wrist and use Apple's published ranges rather than guessing from the model name.
Apple's own UK prices run from £49 for a Sport Loop to £899 for the Hermès Satiné Grand H. Materials account for part of it, and the moulded lug connector accounts for more than people expect, since it is machined to the case tolerance. The Hermès end of the range is a fashion product rather than a technical one.
Yes, 44mm, 45mm and 46mm straps fit a 49mm Ultra. Apple's own guidance is that those sizes should only be worn for casual, everyday use, and that the 49mm Ocean Band, Alpine Loop and Trail Loop are the straps designed for rugged activity such as hiking, climbing and diving.
How we know
We are a UK technology retailer and we sell Apple Watch straps, which is exactly why the numbers on this page come from Apple rather than from our own product listings. Every fitting rule, case size and wrist measurement above was read on Apple's own support and store pages on 16 August 2026, and each source is linked below.
Where Apple's pages disagree with each other, on the meaning of 42mm, we have said so and shown both. Apple is expected to announce new Apple Watch models in September 2026. If the case sizes change, the tables on this page will be updated.
Sources
- Apple, Change your Apple Watch strap: the compatibility groups, the removal steps, the Ultra casual use note, the Milanese Loop 2018 redesign and the Solo Loop sizing advice.
- Apple, Identify your Apple Watch: the case size of every model, including Series 11 at 42mm and 46mm and SE 3 at 40mm and 44mm.
- Apple, Apple Watch Straps: current UK prices and which straps are locked to a single case size.
- Apple, 46mm Black Sport Band: the wrist size ranges and the 44mm, 45mm, 46mm and 49mm compatibility list.
