Does Firebase charge you for just updating fields in Cloud Firestore?

Question

Base on the Firebase Billing system they are only charging for read, writes and deletes in Cloud Firestore. Do they charge for just updating a field in a document in Firestore?

Answer 1

According to this documentation:

Charges for writes and deletes are straightforward. For writes, each set or update operation counts as a single write.

Just to add, if you're update or set has failed then you're not charged as there's not any document change.