Email Marketing ROI Calculator

The full revenue chain

Monthly revenue = emails sent × click rate × conversion rate × average order value

Watch the click rate, because it gets measured two different ways and the gap between them is about a factor of four. The figure on a Mailchimp or Klaviyo dashboard is usually clicks divided by everyone the mail reached, which sits around 2 to 3%. Click-to-open rate divides by the people who opened it instead, and that lands nearer 10 to 15%. Multiplying an open rate by a plain click rate counts the opening step twice and understates the revenue badly. The dropdown above is there so the calculator knows which number you handed it.

A list of 5,000 sending four times a month, a 3% click rate measured against everyone delivered, a 2% conversion rate and an $80 average order value: 5,000 × 4 × 0.03 = 600 clicks, × 0.02 = 12 orders, × $80 = $960 a month. The percentages compound, so doubling the conversion rate alone doubles the revenue.

Benchmarks (Mailchimp and HubSpot 2024 industry data)

Open rates stopped being reliable when Apple Mail Privacy Protection launched in 2021. Apple silently pre-fetches images for its users, which registers an “open” whether anyone read the mail or not. Most lists now show inflated open rates, 35 to 50% reported where real engagement is 20 to 25%. Click rate and conversion rate are the numbers to trust.

Revenue per email subscriber (RPE)

The long-standing rule of thumb is about $1 per subscriber per month for a well-monetised list, so a 5,000-person list “should” produce around $5,000 a month. The top quartile of e-commerce lists run $2 to $5 per subscriber per month and the bottom half do far less, often under $0.30. Mind the units on that: quoted per year it would be $12 to $60, and the two forms get mixed up constantly. This page reports per month.

Reaching $1 takes more than frequency. Four sends a month at a 3% click rate and an $80 order value needs roughly one clicker in ten to buy before the figure gets there. If your result comes out low with healthy open and click rates, the offer is what needs work, not the send calendar. List quality, meaning engagement and segmentation and recency, matters far more than raw size.

Where senders leave money

• Sending too rarely. Once a month is not enough to stay top-of-mind. Twice a week is closer to optimal for most retail, with one well-written newsletter plus one promotional/transactional.
• Sending too often. Daily mail to a non-content list causes fatigue and unsubscribes. Watch the unsubscribe rate per send, and cut frequency if it climbs over 0.3%.
• No segmentation. Sending the same email to a brand-new subscriber and a five-year customer is wasted reach. Segmented campaigns generate 760% more revenue (Campaign Monitor study, 2019).
• Weak subject lines. Open rate is decided in 30 to 50 characters of preview text. A/B test every send, because even a 5% lift compounds.
• Forgetting mobile. Over 60% of email opens happen on mobile. If your email looks bad on a phone, the click never happens.

ROI calculation

ROI % = (revenue − platform cost) ÷ platform cost × 100

A $5,000 monthly revenue against a $100 Mailchimp plan is a 4,900% ROI. Email genuinely is the highest-return marketing channel there is. Industry studies keep measuring average returns of $36 to $42 per $1 spent, far ahead of paid social or display, and the reason is simply that you already own the list. Every other channel rents its audience back to you each time.