Lug-to-lug is the length of a watch case from the tip of the top lugs to the tip of the bottom lugs. It tells you how much of your wrist the watch will cover from one edge to the other, and it predicts fit better than diameter does. As a rule, a watch fits when its lug-to-lug length is no greater than the flat width of the top of your wrist.
Diameter is the number everyone quotes, and it is the less useful of the two. Two watches of 40 mm can differ by several millimeters in length, and it is the long one that looks too big. This guide explains the measurement and how to use it.
What lug-to-lug means
The lugs are the four projections on a watch case that hold the strap or bracelet. They extend above and below the round part of the case.
- Diameter is the width of the case, measured across, not counting the crown.
- Lug-to-lug is the full height of the case, lugs included, measured top to bottom.
- Lug width is something else again: the gap between a pair of lugs, which is the width of strap the watch takes.
Because the lugs stick out beyond the circle of the case, the lug-to-lug length is always greater than the diameter, usually by 6 to 10 mm on a round watch.
Why lug-to-lug matters more than diameter
Your wrist is flat on top for a certain width and then curves away. A watch whose lugs reach beyond that flat area cannot sit down properly: the ends of the lugs hang over the edge, a gap appears between the strap and your wrist, and the watch looks as if it is perched on you.
Diameter does not tell you this, because lugs vary so much. Some watches have short, stubby lugs. Others have long, elegant ones. A 38 mm dress watch with long straight lugs can be longer than a 40 mm sports watch with short curved ones.
How to measure your wrist
You need a ruler and half a minute.
- Rest your forearm on a table, palm down.
- Lay the ruler across the top of your wrist, just above the wrist bone, where you wear a watch.
- Read the width of the flat part, from where your wrist starts to curve down on one side to where it curves down on the other.
That number is your comfortable maximum for lug-to-lug. If you only know your wrist circumference, this rule of thumb is a starting point:
| Wrist circumference | Comfortable lug-to-lug |
|---|---|
| 6 inches (about 15 cm) | Up to about 46 mm |
| 6.5 inches (about 16.5 cm) | Up to about 48 mm |
| 7 inches (about 18 cm) | Up to about 50 mm |
| 7.5 inches (about 19 cm) | Up to about 52 mm |
Wrists differ in shape, flat or round, so measure your own. These figures are guidance, not a standard.
Typical lug-to-lug lengths
To give a sense of scale, these are approximate figures for some well-known watches. The Cartier figures are Cartier's own; the others are commonly quoted measurements and can vary slightly by source.
| Watch | Diameter | Lug-to-lug |
|---|---|---|
| Cartier Santos, Medium | 35.1 mm | 41.9 mm |
| Cartier Santos, Large | 39.8 mm | 47.5 mm |
| Tudor Black Bay Fifty-Eight | 39 mm | About 48 mm |
| Omega Speedmaster Moonwatch | 42 mm | About 47.5 mm |
| Rolex Submariner, current | 41 mm | About 48 mm |
Two things stand out. The Speedmaster is 42 mm across and no longer than the 39 mm Black Bay Fifty-Eight, which is why so many people with medium wrists find it wears smaller than expected. And the Santos Large, under 40 mm wide, is as long as either.
Three things that change how the number feels
Lug-to-lug is the best single measurement, and it still needs interpreting.
Lug shape
Lugs that curve down follow the wrist, so a watch can be a millimeter or two longer than your flat width and still sit well. Lugs that run straight out, as on a Nomos Tangente, do not, and the full length counts.
Integrated bracelets and end links
On a watch with an integrated bracelet, such as a Tissot PRX or a Cartier Santos, the first links are part of the design and barely bend. The watch behaves as though it were longer than its case.
The same is true, to a smaller degree, of steel bracelets on ordinary watches. The solid end links that fit between the lugs often project a little beyond them. A watch on its bracelet can therefore wear longer than the same watch on a leather strap. If a watch is at the limit for your wrist, a strap may solve it.
Thickness
A slim watch hides its size. A thick one draws attention to it. Two watches with the same lug-to-lug length will not look the same if one is 9 mm tall and the other 15 mm.
How to use lug-to-lug when you buy
- Measure your wrist's flat width once and remember it.
- Look up the lug-to-lug length of the watch. Makers do not always publish it, but it is widely recorded for popular models.
- Compare. At or under your flat width, the watch will fit. A millimeter or two over can work with curved lugs. More than that will overhang.
- Check the thickness as a second test.
- Use our Real size button. Every product page on our site can show the case at its true size on your screen; hold your wrist beside it.
If the lug-to-lug length is not on a listing, ask us. We can measure the watch before you buy.
When the rule does not apply
Fit is partly taste. A large pilot's watch or dive watch is meant to look substantial, and some people wear them a size up on purpose. Fashion also moves: watches grew through the 2000s and have been getting smaller again. The lug-to-lug rule tells you what will sit correctly, not what you are allowed to like.
For a full guide to diameter, thickness and bracelet fit, see how to choose your watch size. If your wrist is under 6.5 inches, our list of the best luxury watches for small wrists applies these measurements to twelve models.
Frequently asked questions
What does lug-to-lug mean on a watch?
It is the length of the case from the tip of the top lugs to the tip of the bottom lugs. It shows how far the watch reaches across your wrist.
What lug-to-lug is right for my wrist?
No greater than the flat width of the top of your wrist. For a 6.5-inch wrist that is usually up to about 48 mm; for a 7-inch wrist, up to about 50 mm.
Is lug-to-lug more important than diameter?
For fit, yes. Diameter tells you how big the watch looks from the front; lug-to-lug tells you whether it overhangs your wrist.
Is lug-to-lug the same as lug width?
No. Lug width is the gap between a pair of lugs, which is the width of strap the watch takes, such as 20 mm.
Why does a watch feel bigger on a bracelet?
The solid end links of a bracelet often project slightly beyond the lugs and do not bend, so the watch wears longer than it does on a strap.
Can you measure a watch for me?
Yes. Tell us which watch you are considering and we will give you its measurements before you buy.
