Buying a new Apple Watch band should take a minute, yet the sizes printed on boxes, 41 mm, 45 mm, 46 mm, 49 mm, confuse almost everyone. The trick is that the number refers to the watch case, not the band, and that bands work in two compatibility groups. This guide shows how to check your size and which bands fit which series.
Step 1: find your case size
The size is engraved on the back of your watch, next to the sensors. You can also open the Watch app on your iPhone and go to General, then About. You will see a value such as 41 mm or 45 mm. Write it down before you shop.
Step 2: know the two band groups
Apple keeps the band connector the same within each group, so a band made for one size in the group fits the others too.
| Group | Case sizes | Typical models |
|---|---|---|
| Small | 38, 40, 41 mm and 42 mm (Series 10 and newer) | Series 1-3 (38 mm), 4-6 and SE (40 mm), 7-9 (41 mm), Series 10 and newer (42 mm) |
| Large | 42 mm (Series 1-3), 44, 45, 46 and 49 mm | Series 1-3 (42 mm), 4-6 and SE (44 mm), 7-9 (45 mm), Series 10 and newer (46 mm), Ultra (49 mm) |
Watch out for 42 mm: on Series 1-3 it was the large size, while on Series 10 and newer it is the small size. Always check the series, not just the number.
Step 3: check your wrist
Most bands come in one length that fits roughly 130-210 mm wrists. Magnetic and Milanese bands adjust smoothly to any length, while stretchy braided loops depend on a snug fit. If you are between sizes, a magnetic or Milanese band is the safest choice.
Which band type suits you?
- Silicone sport band: light, waterproof and easy to clean. Great for workouts and sleep tracking.
- Nylon and braided loops: soft, breathable and comfortable all day.
- Milanese loop: fine stainless steel mesh with a magnetic closure, smart enough for the office.
- Steel and ceramic link bracelets: a classic watch look with adjustable links.
You can browse all our smartwatch bands by size. Silicone bands start at β¬34.99, nylon bands are β¬49.99 and Milanese loops β¬59.99, all with free shipping to Europe and the US.
How to change the band
- Turn the watch over and press the small release button next to the band.
- Slide the old band sideways out of the slot.
- Slide the new band in until you hear or feel a click.
No tools are needed and the whole swap takes about ten seconds.
Frequently asked questions
Does a 41 mm band fit a 40 mm watch?
Yes, both are in the small group.
Does a 45 mm band fit an Apple Watch Ultra?
Yes, 45 mm and 49 mm are in the large group. Ultra-specific bands may look slightly wider on a 45 mm case.
Are bands for Series 10 different?
Series 10 and newer use 42 mm (small group) and 46 mm (large group). Pick the band for your group and it will fit.
