Definition
Email revenue per open measures the average revenue generated for each unique open of a campaign. It divides total attributed revenue by the number of unique opens, linking an engagement signal directly to financial output. This metric helps senders understand whether the people who open their email are actually converting into revenue, and how efficiently opens translate to value.
How It Works
Revenue per open builds a bridge between engagement and economics. An open-rate tells a sender how many people saw the message, but not what that attention was worth.
- Engagement quality — a high revenue per open means the message converts the attention it earns, while a low figure suggests opens are not turning into purchases.
- Offer relevance — the metric reflects how well the content and offer match the audience that actually opened.
- Normalisation — by dividing by opens rather than sends, the metric isolates conversion efficiency from raw deliverability.
Because opens are an increasingly unreliable signal — with image blocking and privacy features suppressing tracking — revenue per open should be read alongside click-through-rate and revenue-per-email for a complete picture.
How to Calculate
Calculate revenue per open in three steps:
- Sum attributed revenue — total the revenue credited to the campaign within the attribution window.
- Count unique opens — count the number of unique recipients who opened the campaign.
- Divide — divide revenue by unique opens.
Revenue Per Open = Total Attributed Revenue / Total Unique Opens
| Variable | Description |
|---|---|
| Total Attributed Revenue | Revenue generated from the campaign's conversions |
| Total Unique Opens | Number of unique recipients who opened the email |
Example
A campaign generates £8,000 in attributed revenue and records 20,000 unique opens. Dividing £8,000 by 20,000 gives a revenue per open of £0.40. Comparing this against the sender's average of £0.25 reveals the offer resonated unusually well with openers, suggesting a template worth repeating.
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Frequently Asked Questions
It is useful for comparing campaigns, but opens themselves are imperfectly tracked due to privacy features and image blocking. Treat it as a directional indicator rather than a precise figure.
Revenue per open measures value per reader who opened, while revenue per click measures value per recipient who clicked through. Click-based metrics reflect deeper intent and are often more meaningful for conversion analysis.
It often means the offer or content is not converting the attention it earns, or that opens are inflated by factors other than genuine interest. Reviewing the offer, the landing page, and the audience match can help diagnose the cause.
Improving offer relevance, matching content to the opened segment, and strengthening the call to action all help. Sending to engaged subscribers who are most likely to convert also raises the metric.