Klaviyo Subscriber-Count Margin Trap

Klaviyo bills on active subscriber counts, not flat seats, so a client's list growth quietly raises the platform cost the agency absorbs. The Free plan covers 250 active profiles and 500 emails/month; the Email plan starts at $30/month for an estimated 1,000 active profiles and 10,000 emails/month. A boutique retailer that grows from 1,000 to 20,000 subscribers can multiply the Klaviyo line item several times over while the agency's $550/mo Email Starter fee stays fixed. The framework: before signing, model the client's 12-month list trajectory against Klaviyo's tiered pricing, then either cap the retainer to a subscriber band or pass platform cost through at cost-plus. Agencies that skip this step watch delivery margin erode as the client's success becomes the agency's expense. Pair it with the 16h setup and 4h/mo effort in the Email Starter offer to see true contribution margin per account.