Is there a cost for a subscription to the Calendar to use on all my devices?

Hello freshe,

Thanks for reaching out to us with this inquiry about using the calendar on all your devices. We're happy to help. So we can clarify, are you referring to the native Calendar app? If so, there is no charge by Apple to use this application. You can get more info on using the Calendar app across all of your devices here:

Keep your Calendar up to date with iCloud

Feel free to reach back out if you have any questions.

Best regards!