Do You Need to Replace the Mainspring with Every Service?

 In Watchmaking

When you’re servicing a watch, you have two choices. Clean and reuse the old mainspring or fit a new one.

Both options have their pros and cons.


  • You don’t need tools like mainspring winders because you can simply fit the new mainspring. This will save you a substantial amount of money because these tools are expensive.
  • There’s no risk of the old mainspring breaking after a while, so you avoid having to repair the watch and service it again.
  • Modern mainsprings are much higher quality than the older ones so the performance of your watch will likely improve.
  • It saves you time because you don’t have to clean, lubricate, and fit the old mainspring.
Change the mainspring during every service?

This is an old “blue” type mainspring that has set. It doesn’t have the S-shape that modern mainsprings have.


  • Mainsprings need to have specific dimensions, and the mainspring you need might not be available anymore.
  • Every time you service a movement, you need to buy a new mainspring as well, and that adds up.
  • A very picky collector might feel that the watch loses some of its originality if you change the mainspring.

As you see, it saves you time and money if you fit a new mainspring during a service. A new mainspring will cost you as well, but a good set of winders is at least $600. You can buy a lot of mainsprings for that.

Also, if you decide to reuse the old one and it breaks after one or two years, you’ll have to fit a new mainspring anyway and service it again. In the end, this would be more expensive than installing a new one in the first place.

Parts like the mainspring and the crystal, for example, are considered to be standard wear parts unless your watch has a very rare signed crystal of course.

I’m a very picky collector myself and I don’t mind a new mainspring at all. Sometimes it’s very hard to tell whether parts have been replaced in the first place. Perhaps it’s already the 4th mainspring, who knows.

All in all

It’s best practice to change the mainspring during every service unless you can’t find a new mainspring with the correct dimension. That’s what service centers do as well.

The mainspring is the power unit for your watch. Without it, it doesn’t run. Don’t try to save 10 to 20 USD every 5 years or so during a service because it’s not worth it.

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    Melvin, can you describe to me the signs of a mainspring that should be replaced, because it’s hard to find a new one in my place. Thanks

    • Melvin Hollenberg
      Melvin Hollenberg

      Every old blue type mainspring needs to be replaced. Every mainspring that isn’t perfectly flat on the bench needs to be replaced. The mainspring also needs to be replaced when the first winding isn’t perfectly round anymore.

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