MIGRATION
Switch from Mailchimp to Brevo and change how the billing counts
Subscribers move without much friction; two things need attention. Brevo bills by emails sent, not contacts stored, so your cost model changes and inactive contacts stop being the meter. And Brevo needs your Mailchimp unsubscribes and bounces imported as suppressions, or it will happily mail people who already left. Map audiences and tags, rebuild automations, and test before you switch any form.
BrevoTry Brevo 
MailchimpVisit Mailchimp What transfers, and what you must import
Export your Mailchimp audience with status, opt-in date and source, and import active contacts into Brevo. Brevo keeps unlimited contacts, so storing your whole list costs nothing by itself, but that makes importing suppressions non-optional. Bring unsubscribed and bounced addresses in as suppressed contacts, not active ones, because nothing else stops Brevo from emailing people who already opted out of Mailchimp. Verify counts against your export: active in, suppressions applied, fields intact. Start from the migration checklist so no address is counted as both active and suppressed.
The billing shift you are buying into
Mailchimp charges by contacts stored; Brevo charges by emails sent, with unlimited contacts. That flips your optimisation. On Mailchimp, pruning inactive contacts lowered the bill; on Brevo, a large dormant list is free to hold but every send to it counts. So the lever becomes how often and how widely you mail, not how many names you keep. Model your real sending volume, campaigns times recipients plus automations, before choosing a plan. Compare the same list both ways first: free plan, paid from $13/mo against free plan, paid from $9/mo. Send often to a big list and per-email can cost more; hold a large list and send selectively, and it usually wins.
How the objects map
Write the mapping before importing. A Mailchimp audience becomes a Brevo list; multiple audiences become multiple lists or a field to segment on. Tags map to Brevo lists or to segment conditions depending on how you used them. Merge fields become Brevo contact attributes, matched by type so dates and numbers stay correct. Interest groups collapse into attributes or lists. Automations, welcome, re-engagement, date triggers, are rebuilds in Brevo's automation builder, not transfers. Note anything without an equivalent as a manual job rather than letting the import drop it silently.
Test before you cut over
Import into one test list and check it against your inventory before anything else: active totals, suppressions applied, attributes intact, list membership right. Rebuild a single automation, send a seed campaign, and put a real signup through the form to confirm the contact lands correctly and starts the right flow. Only then repoint forms and integrations at Brevo, let in-flight Mailchimp sequences finish, and keep the old account read-only for a billing cycle as rollback. To see the two pricing models side by side, read Brevo versus Mailchimp.
Questions people also ask
Do I really need to import unsubscribes?
Yes. Because Brevo keeps unlimited contacts, nothing stops it from mailing everyone you import. Bring your Mailchimp unsubscribes and bounces across as suppressions, or you will re-mail people who already left and damage a fresh account's reputation.
Will Brevo be cheaper than Mailchimp?
It depends on your ratio of list size to sending volume. Hold a large list and send selectively, and per-email billing usually wins. Send frequently to your whole list, and it can cost more. Model your real volume before deciding.