Strap material is the decision that changes how a watch feels more than any other. The same watch on leather and on rubber is, in practice, two different watches.
Here is how the four main options actually behave once you live with them.
Leather
Best for: dress watches, vintage pieces, daily wear away from water.
Leather is the only one of the four that improves. It takes the shape of your wrist, darkens where you handle it, and develops a patina no two of which are alike. A good leather strap at two years old looks better than it did new.
The trade-off is water. Leather and prolonged moisture do not get along — repeated soakings will stiffen it, and sweat will eventually break down the fibres from the inside. If you swim in your watch, leather is the wrong answer.
Within leather there is real variety: oil-wax pulls up and marks readily, Crazy Horse is deliberately rugged, and goat leather is supple from the first wear with no break-in.
Rubber
Best for: dive watches, sport, hot weather, anything wet.
Rubber is completely indifferent to water, cheap to replace, and grips the wrist without needing to be tight. It is the practical choice and it knows it.
Standard silicone rubber has two well-known faults: it attracts dust and lint like nothing else, and cheaper compounds can develop a smell over time. Both are manageable — a rinse under the tap fixes most of it — but they are real.
FKM rubber
Best for: people who want rubber without the drawbacks.
FKM (fluoroelastomer — the family Viton belongs to) is the upgrade. It is denser and firmer than silicone, so it does not magnetise every speck of dust in the room, and it is far more resistant to chlorine, salt water, UV and heat. It also does not go sticky with age.
It costs more, and it is slightly stiffer for the first week. After that it is simply better. Our FKM strap is the one we reach for on dive watches.
Nylon
Best for: summer, field watches, spending very little.
Woven nylon — NATO, seatbelt, sailcloth — is light, breathable, dries in minutes and costs less than everything else here. A NATO also passes underneath the case, so if a spring bar fails the watch stays on your wrist. That is a genuine safety feature, not marketing.
The downsides are bulk and formality. The extra layer under the caseback lifts the watch a few millimetres off the wrist, and nylon never looks dressy. Sailcloth splits the difference: woven texture with a padded backing that sits closer to a leather strap in feel.
Quick comparison
- Wet all the time? FKM, then rubber. Not leather.
- Suit and tie? Leather, in a dark colour, slim profile.
- Hot climate, sweaty wrist? Nylon or FKM — both shrug off sweat that ruins leather.
- Want it to look better in two years? Leather is the only one that will.
- One strap for everything? FKM comes closest, and it is the least romantic answer.
The honest advice
Most people are better served by two cheap straps than one expensive one. A leather strap for the office and a rubber or nylon for the weekend covers almost every situation, and with quick-release bars the swap takes under a minute.
Start with leather straps or rubber & sport straps, or see everything at once.