How to measure watch strap for your Radley London smartwatch

Finding a new look for your wrist is one of the joys of owning a Radley London smartwatch. While the original silicone or leather straps that come with your Series 8 or Series 20 are designed for durability, you might eventually want to swap them for something that better suits a specific outfit or a formal event. Before you buy a replacement, you need to be certain about the size. Knowing how to measure watch strap width is the first step to ensuring your new purchase actually fits the lugs of your timepiece.

Most people assume all smartwatches use a universal size, but even within the Radley range, dimensions can vary between the daintier fashion models and the larger rectangular screens. If you choose a strap that is even one millimetre too wide, it will not fit between the metal shoulders of the watch. Conversely, a strap that is too narrow will slide back and forth on the pin, which looks untidy and can actually cause the spring bar to fail over time. Taking two minutes to measure properly saves you the hassle of returning a strap that doesn't quite work.

Understanding the lug width

When we talk about measuring for a new strap, we are specifically looking for the 'lug width'. The lugs are the two metal arms that protrude from the watch case to hold the strap in place. The distance between the inner faces of these two arms is the exact measurement you need. Radley smartwatches are manufactured by Peers Hardy and generally follow standard industry sizing, which makes finding replacements relatively straightforward once you have your numbers.

For the majority of the Radley collection, you will find that the lug width is either 20mm or 22mm. The smaller, more delicate models often favour the 20mm size, while the sportier or larger rectangular faces typically use the 22mm standard. To get an accurate reading, you should always measure the gap on the watch head itself rather than measuring the old strap, as leather can stretch or shrink slightly after months of wear against your skin.

Tools you will need for an accurate measurement

You do not need professional horological equipment to get this right. A simple metric ruler with clear millimetre markings is usually sufficient. However, if you want to be incredibly precise, a pair of digital calipers will give you a reading down to the decimal point. Avoid using a soft fabric dressmaker's tape for this specific task, as these can stretch and lead to a measurement that is off by a millimetre or two, which is enough to cause fitment issues.

Place your watch face down on a soft cloth to prevent the screen from scratching. Align the 'zero' mark of your ruler with the inside of one lug and read the distance to the inside of the opposite lug. Ensure you are measuring the gap where the pin sits, not the outer width of the watch case. This internal measurement is the only number that matters when browsing for third-party straps.

Step by step guide to measuring your strap

1. 1
   Remove the existing strap by sliding the quick-release pin inwards.
2. 2
   Lay the watch head on a flat, soft surface like a microfiber cloth.
3. 3
   Use a metric ruler to measure the distance between the inside of the lugs in millimetres.
4. 4
   Note down the measurement, which will likely be 18mm, 20mm, or 22mm.
5. 5
   Measure the length of your current strap if you have particularly large or small wrists to ensure the new one will buckle comfortably.

Measuring for wrist comfort and strap length

While lug width ensures the strap attaches to the watch, the length of the strap ensures it actually fits you. Most Radley straps are 'standard' length, which accommodates a wide range of wrist sizes. However, if you find your current strap is on the very last hole or has too much excess 'tail' flapping around, you might want to look for a 'short' or 'long' version of your chosen style.

To measure your wrist, wrap a flexible measuring tape around the area where you usually wear your watch—typically just behind the wrist bone. Do not pull it too tight; it should be snug but comfortable. If you don't have a flexible tape, use a piece of string, mark the overlap, and then measure the string against a flat ruler. Most Radley smartwatches work best when the sensors on the back have consistent contact with your skin, so a well-fitted length is vital for accurate heart rate tracking.

Checking for quick release compatibility

Modern Radley London smartwatches, including the Series 32 and 33, almost always use quick-release spring bars. These are fantastic because they allow you to change your look in seconds without using any tiny screwdrivers or prying tools. When you measure your strap and go to buy a replacement, look for straps that explicitly mention 'quick release' or have the small visible knob on the underside of the strap.

If you fall in love with a traditional watch strap that doesn't have this feature, you can still use it, but you will need a standard set of 20mm or 22mm spring bars and a small spring bar tool to click it into place. For simplicity's sake, we always recommend sticking to the quick-release variety, as it makes cleaning your watch and rotating your style much more enjoyable.

Commonly asked questions

Taking the time to measure your watch strap properly ensures that your Radley London smartwatch remains a comfortable and stylish companion. Whether you are switching to a breathable silicone band for the gym or a sophisticated rose gold mesh for a night out, that 20mm or 22mm measurement is your key to a perfect fit. Keep a note of it in your phone so you are always ready when a new style catches your eye.