How much does it cost to replace the watch face if cracked?

Hi

Apple Watch (not iwatch) is not user-serviceable and Apple does not offer a screen repair or screen replacement service for Apple Watch.

If the issue is not covered under warranty or any other Apple policy, then your Apple Watch may instead be eligible for replacement via chargeable, out-of-warranty service (or via AppleCare+, if previously purchased).

Contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider to arrange for your Apple Watch to be inspected and to establish your available service options:

• US: Apple Watch Service Answer Center - Apple Support
• Elsewhere: Select your country for Apple Watch service and repair information

Out-of-warranty repair service prices vary, depending on your location and model. Prices in the US, for example, are available here:

Apple Watch Service Pricing - Apple Support

In the meantime, note that Apple advises that you should not continue using a damaged Apple Watch.

See this for pricing information. https://support.apple.com/watch/repair/service

Apple does not repair the crystal, they replace the Apple Watch. Follow the steps in that link.