A new strap for your Apple Watch, Samsung, Garmin or Fitbit — here's what you need to know
Does your heart rate monitor still work accurately with a different strap? Will contactless payments keep working? And which connector size do you actually need? This guide answers the questions you have but perhaps didn't know to ask.
1. Do the sensors still work normally with a different strap?
This is the question we get asked most often — and the answer is reassuring: yes, absolutely. The sensors in your smartwatch — such as the heart rate monitor, SpO2 and ECG — are built into the watch itself, not the strap. Swapping the strap only replaces the part that sits around your wrist, not the technology inside the watch.
What does matter is that the strap fits well. A strap that's too loose, or that causes the watch to tilt on your wrist, can disrupt sensor readings — regardless of the brand or material of the strap. More on that in point 3.
2. Can I still pay with my watch?
Yes. NFC — the technology that lets you pay contactlessly with your watch — is also built into the watch itself and isn't affected by the strap at all. You can keep tapping away at the till, no matter which strap you're wearing.
Imperial Chakra Apple Watch Band
3. How tight should the strap be for the best reading?
This is something a lot of people don't think about, but it makes a real difference. The optical sensor on the back of your watch needs consistent contact with your skin to measure accurately. If the strap is too loose, the watch shifts with every movement of your wrist — and that disrupts the reading.
The general rule of thumb:
- The strap shouldn't slide or rotate on your wrist
- You should just be able to slide one finger between the strap and your wrist — no more
- During exercise, it can sit slightly tighter than usual for more stable readings
One more thing to bear in mind: a strap that's too rigid, or that doesn't bend comfortably around your wrist, can cause the watch to tilt slightly. That might sound harmless, but if the sensor on the back isn't lying flat against your skin, you'll lose measurement accuracy. Choose a strap that moves naturally with the shape of your wrist.
4. Does the strap block the buttons or the sensor on the back?
Two things to look out for when choosing a strap:
The optical sensor — The strap connector must not cover the sensor windows on the back of your watch. Our straps are designed with this in mind: the connector fits seamlessly onto the watch without blocking the sensor. Always make sure you slide the strap in on the correct side — the side with the three black lines is the front and belongs on the screen side. More details in our brand-specific installation guides on our Tips & Tutorials blog.
The buttons on the side — A strap that's too wide for your watch model can physically touch or block the crown or side buttons. Always check the width of the strap against your specific model before making a choice.
Mystical Labradorite Apple Watch Band
5. Quick Release or QuickFit — what's the difference and why does it matter?
This is one of the most common mix-ups when ordering a new strap — and it can mean your strap simply won't fit, even if the size is otherwise correct.
- Quick Release is the system used by Apple, Fitbit and most other brands. You slide the strap into the connector on the side of the watch and it clicks into place — no tools needed.
- QuickFit is Garmin's own system. It works differently and is not interchangeable with Quick Release.
Important: We only offer Quick Release straps — not QuickFit. Got a Garmin? Make sure to check which connector system your specific model uses before ordering.
6. Which connector size do I need?
The width of the connector — also known as the lug width — is the point where the strap attaches to the watch. This measurement varies per model and determines which strap will fit. For Samsung, Garmin and Fitbit, this is either 20mm or 22mm. For Apple Watch, it depends on your case size.
How to find your size:
- Check the back of your smartwatch — the case size is often printed there
- Or open the Watch app on your phone → General → About → Model details
- Then use our SIZE GUIDE to determine the correct size and connector in three steps
⚠️ Note for Apple Watch Series 10 & 11: the sizing logic here is the opposite of what you'd expect. Got the 42mm? Choose the 38/40/41mm variant. Got the 46mm? Choose the 42/44/45/46/49mm variant. Our size guide walks you through this step by step.
Dreamy Jasper Samsung Watch Band
7. Can you exercise with your strap?
Yes — but there are a few things to bear in mind. Prolonged contact with sweat can affect some materials over time. Our straps are made from genuine natural stones and a stainless steel connector, which is more robust than you might expect. Read our care guide for specific tips on exercising, sweat and how to keep your strap looking its best for as long as possible.
8. One more reason to choose mindfully: what's sitting against your skin?
Most standard smartwatch straps are made from silicone — a non-breathable material that traps sweat, heat and bacteria against your skin. If you wear your watch every day, that's quickly 16 hours a day of skin contact with a material that doesn't let any air through. This can lead to skin irritation, redness or itching — something many daily wearers will recognise but don't always connect to their strap.
Our straps are made from 100% genuine natural stones. Air circulates between the stones, allowing sweat to evaporate rather than becoming trapped — a noticeable difference you'll feel after just one day of wearing.
Ready to find your perfect strap?
Use our SIZE GUIDE to choose the correct wrist size, connector and watch variant in three steps — for Apple, Samsung, Garmin and Fitbit.
Can't work it out? Drop us a message at support@kejama.com — we're here to help. 💛
