Definition
Cost per conversion (CPC or CPA) represents how much you spent for each desired action — a purchase, sign-up, download, or other conversion event. It includes all campaign costs: platform fees, creative production, copywriting, and management time.
Formula
Cost Per Conversion = Total Campaign Cost / Total Conversions
Benchmarks
Email typically achieves a much lower cost per conversion than paid channels because you are reaching an opted-in audience rather than paying for each impression or click. Average email CPA varies by industry from £5-£50 for ecommerce and £20-£200 for B2B.
Why It Matters
Tracking cost per conversion prevents the common mistake of celebrating revenue without accounting for the cost required to generate it. A campaign with high revenue but even higher cost is actually destroying value.
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
ARPU (Average Revenue Per User)
ARPU (Average Revenue Per User) is a metric that measures the average revenue generated per email subscriber over a specific period, used to evaluate list value and campaign effectiveness.
Attention Rate
Attention rate is the percentage of email opens that last longer than 5 seconds, distinguishing genuine reads from passive opens, preview-pane views, or Apple MPP auto-loads.
Bounce Rate Threshold
A bounce rate threshold is the percentage of hard or soft bounces at which email platforms and ISPs begin to penalise sender reputation, typically around 2-5%.
Bounce Rate
Email bounce rate is the percentage of emails that were rejected by the receiving server before reaching the recipient. It is a key indicator of list health and data quality.