Mailchimp's peak-contact billing, explained

Mailchimp's pricing has a quirk that catches people off guard: it bills on the peak contact count during your billing period, and that count includes unsubscribed and non-subscribed contacts.

The peak ratchet

Hit a higher contact tier for even a single day — a big import, a campaign spike — and you're charged for that tier the whole month. The count ratchets up to your peak and bills from there.

Dead contacts count too

Unsubscribed and non-subscribed contacts stay in your billable audience. Only cleaned contacts fall out. So a list that's 30% unsubscribed is still billing you at the full size.

Archiving an un-emailable contact removes them from the billable count — reversibly. For mid-to-large lists, that can drop you a whole tier, which is real money every month.