You grew your list. Why did your bill grow faster?

Prices are the published tiers from each platform's public pricing pages — klaviyo.com/pricing, omnisend.com/pricing, brevo.com/pricing (all captured August 18, 2026) and mailchimp.com/pricing (US-market prices from its official pricing page, verified March 2026 via archived capture; Mailchimp prices vary by region). No interpolation: the calculator selects the smallest published tier that fits your inputs. Klaviyo bills on active profiles stored (suppressed profiles excluded) and includes roughly 10× your profile count in monthly sends; above 150,000 profiles Klaviyo is sales-only. Omnisend bills on contacts — including non-subscribers such as abandoned carts — with a send cap of 12× contacts on Standard; the calculator switches to Pro when your volume exceeds it. Brevo bills on emails sent; each tier includes a contact allowance (up to 500,000 on Starter/Standard, 2 million on Professional) and the calculator picks the tier that fits both your sending and your list. Mailchimp Standard supports up to 100,000 contacts; larger lists require Premium. At volumes up to 9,000 emails/month the calculator shows Brevo's permanent Free plan ($0, 300 emails/day, up to 100,000 contacts stored); campaigns to more than 300 recipients send in daily batches on the Free plan. Klaviyo, Omnisend and Mailchimp also offer free tiers (roughly 250–500 contacts); they fall below this calculator's 500-contact minimum. Annual view applies Brevo's published 10% yearly discount to Brevo only. The List Tax is an estimate: it assumes an engaged contact receives about 4 emails per month, so contacts reached ≈ monthly emails ÷ 4; ghost contacts are those stored beyond that, and the List Tax is the difference between Klaviyo's published price for your full list and its price for only the contacts you reach. 'You'd save' is not an estimate — it is the difference between Klaviyo's and Brevo's published prices at your inputs. All trademarks belong to their owners; figures are estimates, not quotes.