Definition
Subscriber payback period answers: how long until a new subscriber earns back what it cost to acquire them? If you spend £5 to acquire a subscriber and they generate £1 per month in revenue, your payback period is 5 months.
Formula
Payback Period (months) = Acquisition Cost / Monthly Revenue Per Subscriber
Why It Matters
A long payback period ties up cash in list building. A short payback period means your acquisition strategy is efficient. Benchmarks vary by industry: ecommerce typically aims for 3-6 months, SaaS for 6-12 months. Tracking this metric helps you set realistic acquisition budgets and evaluate channel performance.
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.
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
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.
Campaign Internal Rate of Return (IRR)
Campaign IRR is the annualised return rate earned by an email campaign, accounting for the timing and magnitude of costs and revenue across the campaign's full lifecycle.
Campaign Lifted Revenue
Campaign lifted revenue is the additional revenue generated by an email campaign beyond what would have occurred without it, measured via a holdout group or statistical lift analysis.