You've got the watch. Now let's get the strap right.
Whether you're replacing your first watch strap or building a rotation for different occasions, this guide covers the basics — lug width, taper, buckle size, keepers, and spring bars. At JackCoHenry, these are the terms and decisions that come up in every commission conversation. Start here.
What Is a Watch Strap?
A watch strap is the band that attaches your watch case to your wrist. The right strap should fit securely between the lugs, sit comfortably on your wrist, and complement the style of your watch.
Before choosing a strap, it helps to understand the key parts that affect fit, comfort, and appearance.
Key Parts of a Watch Strap
Lug Width: The lug width is the distance between the two lugs of your watch case. This measurement determines which strap width will fit your watch. For example, if your watch has a 20mm lug width, you'll need a 20mm strap.
Taper: Taper refers to how the strap narrows from the lug end to the buckle end. A 20/18mm strap means it is 20mm at the lugs and tapers to 18mm at the buckle. A stronger taper gives the strap a more refined, elegant look.
Keeper: The keeper is the loop that holds the strap tail in place after you fasten the buckle. Most straps have one fixed keeper and one floating keeper.
Buckle: The buckle secures the strap around your wrist. Buckle size is usually determined by the strap's buckle-end width.
Spring Bars: Spring bars are the small metal pins that attach the strap to your watch case. They sit inside the lugs and hold the strap in place.
Common Watch Strap Styles
Straight-End Strap: A straight-end strap has a clean, classic edge where it meets the watch case. It is versatile and works with most watches.
Curved-End Strap: A curved-end strap follows the shape of the watch case for a more integrated look. These usually need to match the specific case shape closely.
Tapered Strap: A tapered strap narrows from the lugs to the buckle. This creates a more elegant profile and is often preferred for dress watches.
Explore our full range of leather colours, textures, and finishes in our Material Hub on Telegram.
How Should a Watch Strap Fit?
A watch strap should sit flush against the case, with no obvious gaps at the lugs. The strap should not twist under the case, and the buckle should sit comfortably near the centre of your wrist when fastened.
If the strap gaps at the lugs, feels unstable, or does not sit evenly, the width or length may not be right for your watch.
Need help checking your fit?
→ Go to the Fit Guide
How to Measure Your Watch Strap Size
To find the right strap size, start by measuring your lug width. This is usually measured in millimetres, such as 18mm, 20mm, 21mm, or 22mm.
You should also consider strap length, especially if you have a smaller or larger wrist. The right length helps keep the buckle centred and prevents the strap tail from being too short or too long.
Need help measuring your lug width or finding the right strap length?
→ Go to the Sizing Guide
How to Change a Watch Strap
Changing a strap takes about two minutes with the right tool. Compress the spring bar at each lug with a spring bar tool, slide the old strap free, then snap the new one in.
Not sure how? Read our step-by-step guide to changing your strap.
Frequently Asked Questions
Q. How do I know what strap size my watch needs?
Measure the lug width of your watch in millimetres. The strap width should match the lug width exactly.
Q. What does 20/18mm mean on a watch strap?
It means the strap is 20mm wide at the lugs and tapers to 18mm at the buckle.
Q. Can any strap fit any watch?
Not always. The strap must match your watch's lug width, case shape, spring bar setup, and preferred strap length.
Q. What is the difference between straight-end and curved-end straps?
A straight-end strap has a flat edge and works with most watches. A curved-end strap follows the curve of the watch case and needs a closer case-specific fit.
Q. Do I need a tool to change my watch strap?
Most straps require a spring bar tool. Quick-release straps may be changed without tools, depending on the design.
Ready to Go Deeper? Read These Next
Now that you know the basics, these JackCoHenry guides will take you further:
→ Will Your Strap Fit My Watch? — check attachment style, lug width, and curved lugs before ordering
→ Watch Strap Sizing Guide — get your exact measurements for S, M, or L — or a custom length
→ How to Change Your Watch Strap Buckle — swap to a pin buckle or deployant clasp in under two minutes
Still Have Questions?
Our FAQ covers ordering, sizing, materials, strap care, and custom requests.
Find Your Strap
Ready to choose your next strap?