Mailchimp, Klaviyo or Brevo: the one number that decides which is cheapest

Comparing the headline plans of Mailchimp, Klaviyo and Brevo is misleading, because the three do not price the same way. Mailchimp and Klaviyo charge by how many contacts you store. Brevo charges by how many emails you send, with unlimited stored contacts. So the cheapest option flips depending on one number about you, not about them.

The default scenario

Take the calculator default: a 10,000-contact list that gets 40,000 emails a month, which is four sends per contact. Using the linear rates anchored to June 2026 reference points, here is what the three models cost.

• Mailchimp, by contacts: about 100 dollars a month (10,000 contacts at roughly one cent each).
• Klaviyo, by contacts: about 150 dollars a month (the same list at a higher per-contact rate).
• Brevo, by emails sent: about 32 dollars a month (40,000 sends at roughly 0.80 dollars per 1,000).

These are planning numbers from a deliberately simple linear model, not quotes. Real plans are tiered step functions, so confirm your own current tier from each provider before you commit. The point is the shape, not the cents.

The number that actually decides it

It is your contacts-to-sends ratio: how many emails each stored contact receives in a month. With the default rates, Mailchimp and Brevo cost the same at about 12.5 emails per contact per month. Below that you send relatively little to a large stored list, and Brevo is cheaper. Above it you mail the same people often, and the stored-contact fee is spread over so much sending that contact pricing wins. Klaviyo, priced higher per contact, only catches Brevo above roughly 19 emails per contact per month.

The same list, two ways

• A 50,000-contact list mailed once a month (50,000 sends): about 500 dollars on Mailchimp, 750 on Klaviyo, and 40 on Brevo. A big list you mail rarely is the strongest case for send-based pricing.
• A 2,000-contact list mailed 20 times a month (40,000 sends): about 20 dollars on Mailchimp, 30 on Klaviyo, and 32 on Brevo. A small list you mail constantly is where contact-based pricing turns cheaper.

Not every contact is a billable contact

The deciding number is contacts-to-sends, but the word contacts is not counted the same way by the two contact-priced tools, so the same 10,000-row list can bill very differently. Before you compare, get each tool to tell you its billable count, not your raw list size.

• Mailchimp counts the most. Subscribed, unsubscribed and non-subscribed contacts all count toward your plan; only archived, cleaned (repeatedly bounced) and deleted contacts drop out. So people who opted out keep billing until you act. The lever is to filter by Unsubscribed status and archive them, which removes them from the billable total while keeping the record.
• Klaviyo counts the least of the two. It bills active profiles, and suppressed, unsubscribed and deleted profiles are not active, so they do not count. The catch is that suppression is not automatic: a stale profile you have stopped emailing keeps counting until it unsubscribes or you suppress it, which is the most common reason a Klaviyo bill drifts up.
• Brevo sidesteps the question. Every paid plan includes unlimited contacts and bills on emails sent, so an unsubscribed or dormant contact costs nothing because cost tracks sending, not storage.

The contact bill only climbs on its own

There is a second reason the two contact-priced tools behave differently from Brevo, and it decides what you actually budget. They do not just cost more at a bigger list; they re-price themselves upward as the list grows, without you choosing to upgrade, and neither one lowers the bill on its own when the list shrinks. That one-way ratchet is the practical gap from send-based pricing, where the bill tracks what you do rather than what you store.

• Mailchimp: on a current Marketing plan, going over your tier contact or send limit does not switch plans, it adds automatic overage called an add-on contact block, and if you exceed by more than one block you are billed for several. Billing also tracks the highest contact count reached during the cycle, so a mid-month spike sets the bill even if the list is smaller by month end. Older legacy monthly plans go further and auto-adjust the billing tier upward as the list grows. There is no automatic downgrade on either, so the bill falls only when you archive contacts or move down a tier yourself.
• Klaviyo: since a February 2025 change, crossing an active-profile tier moves you to the next plan at the start of the next billing cycle with no opt-out, and there is no matching auto-downgrade. The bill drops only when you actively suppress or clean profiles.
• Brevo: the send-based bill has no contact ceiling to cross, so storing more contacts never triggers a charge on its own. It rises only when you send more, and falls the month you send less.

So the honest planning number for the contact-priced options is not what you pay today, it is what you will pay at your list at its biggest, because the meter climbs there by itself and stays until you act. With Brevo you budget the opposite way: against the send volume you expect, not the size of the list you keep.

Where Klaviyo still earns its premium

On pure cost Klaviyo is the most expensive of the three in this model, so the honest cost answer is rarely Klaviyo. Its case is not price; it is ecommerce revenue attribution and flows tied to store data. If you are not running that, you are paying for capability you do not use, and the cost math above applies straight.

The second meter this comparison ignores: SMS

The contacts-to-sends ratio decides your email bill, but all three platforms sell SMS and MMS marketing on a completely separate meter. Texts are billed per message as credits, on top of whatever your email tier costs, so switching on SMS means running two bills at once rather than upgrading one. None of the numbers above include a single text.

How the credits work differs in a way worth knowing before you commit. Klaviyo includes a set monthly credit allowance and Mailchimp bills credits in blocks re-purchased each month; on both, unused credits do not roll over, so anything you do not send by the end of the cycle expires. Brevo instead sells prepaid SMS credits that never expire, which suits irregular or seasonal texting. On rates, a US text is cheap on all three, roughly a cent each: Klaviyo counts one credit per US SMS, and Brevo lists about 1.09 dollars per 100 messages to the United States. The per-message price then climbs steeply by destination country, so Klaviyo charges several times more per message to Germany or the Netherlands than to the US, and Brevo lists about 3.45 dollars per 100 messages to the UK.

So if SMS is part of your plan, the cheapest email model is only half the answer. Price the text volume you actually expect, by destination country, as its own line, and remember that a message over 160 characters or one carrying an image counts as more than one credit. The calculator on this page sizes the email side; the SMS side is a separate per-message cost to add on top.

The feature all three now market that does not add a meter: AI

Every one of these platforms now sells AI, so it is worth saying plainly where it lands on the bill: on the email side, it does not. Klaviyo bundles its generative tools (Segments AI, Email AI, SMS AI and a marketing agent) into every paid email tier at no extra charge. Mailchimp includes its Intuit Assist creative assistant on the Standard and Premium plans at no additional cost. Brevo makes its Aura assistant, for subject lines and campaign copy, available on every plan including the free one, and only gates one piece of it, putting automatic AI audience segmentation on its top Professional tier rather than metering it per use. So unlike a CRM that meters AI credits or an observability tool that bills AI features per event, email-marketing AI is folded into the plan you already pay for and does not change the contacts-to-sends math above.

The one place a separate meter does appear is a different product from email marketing: agentic customer-service AI. Klaviyo sells a Customer Agent that answers support conversations, priced on its own at roughly 200 dollars a month for an included 50 conversations, then about 0.70 dollars per conversation beyond that. That is a support-automation line you switch on deliberately, not part of your campaign sending, so it belongs in a different budget. For the email decision on this page, treat AI as a bundled feature, not a meter, and keep the contacts-to-sends ratio as the number that decides the bill. (List prices, checked July 2026, they move.)

The free tiers, and which one runs a real list

The paid decision has a free-tier version of the same question, because all three offer a forever-free plan and they wall it off along the same axis they bill on. The two contact-priced tools cap the free plan on contacts; the send-priced one caps it on daily sends. So which free plan you can actually live on flips on the same contacts-to-sends ratio as the paid choice.

• Mailchimp free: 250 contacts and 500 email sends a month, after a February 2026 cut from 500 contacts and 1,000 sends. Go over the contact limit and Mailchimp holds all sending, live and test alike, until you upgrade or bring the count back down.
• Klaviyo free: 250 active profiles and 500 email sends a month, plus a small monthly allowance of 150 SMS or MMS credits. Cross either the profile or the send limit and sending is restricted until you drop back under 250 profiles or upgrade.
• Brevo free: up to 100,000 stored contacts but a hard cap of 300 emails a day, and every message carries a Sent with Brevo sticker. A campaign to more than 300 recipients only reaches the first 300 that day; you requeue the rest over the following days.

Read against the ratio, the free tiers pull the same way the paid plans do. A small list you mail often fits the 250-contact wall on Mailchimp or Klaviyo, but 500 sends a month is thin: 250 contacts mailed twice is already the whole budget, so a high-cadence list outgrows the free send cap fast. A large list you mail rarely is the opposite: 250 contacts locks Mailchimp and Klaviyo out before you begin, while Brevo will store tens of thousands for free, provided you never need to reach more than 300 of them in a single day, which a real newsletter usually does. So the free plans are useful for trialling the product on either side, but the moment a list is both sizeable and mailed on a schedule, one of them pushes you to paid, and it is the same ratio that tells you which.

Run your own ratio

Drop your real list size and monthly send volume into the calculator and it shows which model, and which provider, is cheapest for you, with every rate editable so you can paste in your own current tier. The decision is your ratio; the tool just does the arithmetic.