Email Performance Calculator: Open, Click and Bounce Rates
Enter one campaign's send numbers to get eight email marketing metrics at once: deliverability, engagement, list health and revenue.
Results
Nothing is required. Each metric appears once the figures behind it are filled in.
Share of sent emails accepted by the recipient's mail server. Accepted does not mean it landed in the inbox.
Share of sent emails that were returned undelivered.
Share of delivered emails that were opened. Inflated by privacy features like Apple MPP.
Of the opens measured, the share that clicked. Privacy features can distort opens, so read it as a trend.
Share of delivered emails that led someone to opt out.
Share of delivered emails marked as spam. Above ~0.1% is a sender-reputation risk.
Net change in list size over the period. Negative when losses exceed gains.
Average revenue per email sent, bounces included.
How to calculate email open rate and CTOR
Open rate = Opens ÷ Delivered × 100
- Delivery rate and bounce rate divide by emails sent: delivered ÷ sent and bounced ÷ sent.
- Open rate, unsubscribe rate and spam complaint rate divide by delivered, because only a delivered email can be opened, unsubscribed from or reported.
- Click-to-open rate divides clicks by opens. List growth uses (new subscribers − unsubscribes) ÷ list size at the start, and revenue per recipient uses revenue ÷ sent.
2,450 ÷ 9,800 = 25.00% open rate · 392 ÷ 2,450 = 16.00% CTOR
What email performance metrics measure
Email performance is the set of numbers that tells you what happened to a campaign after you pressed send. This calculator groups eight of them into four questions. Deliverability (delivery rate and email bounce rate) asks whether the message arrived. Engagement (email open rate and click-to-open rate) asks what people did with it. List health (unsubscribe rate, spam complaint rate and list growth rate) asks what the send cost you in audience. Revenue per recipient asks what one email was worth.
The metrics share denominators, which is why they sit on one page. Sent is the base for three of them (delivery, bounce and revenue per recipient). Delivered is the base for three more (open, unsubscribe and complaint). Opens are the base for click-to-open rate, and the list size at the start of the period is the base for email list growth rate. Entering the same campaign into eight separate calculators is how numbers stop reconciling. Every field is optional: a metric whose inputs you leave empty stays blank instead of showing a zero.
Read together, the metrics point at different causes. A low open rate next to a high bounce rate is a list problem before it is a subject-line problem. A healthy open rate with a weak click-to-open rate points at the content or the offer. Strong revenue per recipient next to a rising complaint rate means the campaign earns today while it spends the sender reputation that future sends depend on.
Email marketing metrics and their formulas
The table lists the eight metrics this calculator returns, the base each one divides by and the result for an example campaign. The example has 10,000 sent, 9,800 delivered, 200 bounced, 2,450 opens, 392 clicks, 20 unsubscribes, 5 spam complaints and $2,000 of attributed revenue. Its list started the period at 10,000 and gained 500 new subscribers. Use it to check that your own report divides by the same base before you compare numbers.
| Metric | Formula | Example result | Group |
|---|---|---|---|
| Delivery rate | Delivered ÷ Sent | 98.00% | Deliverability |
| Bounce rate | Bounced ÷ Sent | 2.00% | Deliverability |
| Open rate | Opens ÷ Delivered | 25.00% | Engagement |
| Click-to-open rate (CTOR) | Clicks ÷ Opens | 16.00% | Engagement |
| Unsubscribe rate | Unsubscribes ÷ Delivered | 0.20% | List health |
| Spam complaint rate | Complaints ÷ Delivered | 0.05% | List health |
| List growth rate | (New subscribers − Unsubscribes) ÷ List size at start | 4.80% | List health |
| Revenue per recipient | Revenue ÷ Sent | $0.20 | Revenue |
Two bases deserve a note. Revenue per recipient divides by sent, which charges the campaign for every address it tried, bounces included. Dividing by delivered gives a slightly higher figure ($2,000 ÷ 9,800 ≈ $0.204) that answers a narrower question about the messages recipient servers accepted. The second is click-to-open rate vs click-through rate, two rates that are easy to swap in a report: CTOR divides clicks by opens, while email click-through rate divides clicks by delivered. In the example that is 16.00% against 4.00%, so the label matters as much as the number.
To calculate email open rate the same way every time, also decide what an open is. Many email platforms report unique opens, which count a person once however many times they open, and total opens, which count every open. Unique opens are the steadier base for comparing campaigns. Apply the same choice to clicks when you work out CTOR.
What to check when an email metric moves
One number moving on its own seldom tells you what went wrong. Before you rewrite subject lines or change the send time, run through these checks:
Mail privacy features: Apple says Mail Privacy Protection prevents senders from seeing whether you opened their message (Apple Support: Mail Privacy Protection). A shift in how many of your subscribers use it can move open rate with no change in real interest. Apple also notes that the feature does not extend to links, so clicks remain the firmer signal.
Bounces before opens: when bounces rise, fewer emails are accepted by recipient mail servers and every delivered-based metric changes its base. Remove hard bounces from the list before comparing campaigns.
Spam complaints: Google's sender guidelines ask senders to keep the spam rate reported in Postmaster Tools below 0.10% and to avoid ever reaching 0.30% (Gmail email sender guidelines). Postmaster Tools calculates its own figure, so use your complaint rate as an early warning and watch the trend across sends.
Segment and timing: compare sends to the same segment on similar days. A re-engagement campaign to inactive subscribers will look weaker than a send to recent buyers even when the email itself is better.
Whatever survives these checks points to a real change in the content, the offer or the audience. Tag every link with UTM parameters using the UTM builder so you can follow clicks into analytics, then measure what happens after the click with the conversion rate calculator. Revenue per recipient tells you what a send earned, and ROAS tells you whether the paid tools and promotions behind it paid for themselves.
When to use the email performance calculator
Use it right after a send to read one campaign as a whole, and across sends to see which of the four groups moved when a headline number changed. You do not need every field: enter sent, delivered and opens to get delivery and open rate, then add clicks, revenue and list figures as they come in. It also works as a quick audit of a platform report, because entering the raw counts shows which base each reported rate used.
Where email metrics mislead
Open rate is the least reliable of the eight, because privacy features in mail apps hide or distort opens. Read it as a trend against your own history. Reporting click-to-open rate as click-through rate makes the example campaign look four times stronger than it is. A delivered count higher than the sent count is a data error. Mixing date ranges or segments can produce it.
Guides on this topic
Frequently Asked Questions
How do you calculate email open rate?
Divide opens by delivered emails and multiply by 100: Open rate = Opens ÷ Delivered × 100. In the example, 2,450 opens from 9,800 delivered emails give a 25.00% open rate. Decide whether you count unique opens or total opens and keep that choice fixed. Some tools divide by sent instead of delivered, which gives a lower rate for the same campaign, so check the base before you compare reports.
What is the difference between click-to-open rate and click-through rate?
Click-to-open rate (CTOR) divides clicks by opens, so it measures how convincing the content was for the people who opened. Email click-through rate (CTR) divides clicks by delivered emails, so it combines the subject line's pull with the content's pull. In the example, 392 clicks give a 16.00% CTOR against 2,450 opens and a 4.00% CTR against 9,800 delivered. Both are valid. The mistake is reporting one under the other's name, because CTOR is always the higher of the two when opens are fewer than delivered emails.
Is email open rate still reliable after Apple Mail Privacy Protection?
Less than it used to be, but it still works as a trend. Apple says Mail Privacy Protection prevents senders from seeing whether a message was opened, so opens from subscribers who use it no longer reflect real reading. The effect stays fairly stable within one audience, which means comparing your own campaigns over time still carries signal. Comparing your open rate with another company's, or with a published average, carries much less. For decisions about content, rely on clicks, click-to-open rate and revenue per recipient.
What is an acceptable spam complaint rate?
Google's email sender guidelines ask senders to keep the spam rate reported in Postmaster Tools below 0.10% and never to reach 0.30%. Senders who send more than 5,000 messages a day to Gmail accounts must stay below 0.30%. Treat 0.10% as a ceiling to stay well under. The example campaign's 5 complaints from 9,800 delivered emails give 0.05%. Because the damage shows up later as weaker deliverability, a complaint rate that rises across several sends deserves attention before it crosses any line.
What is a good email open rate?
There is no reliable universal number. Open rate depends on the audience, the industry, the type of email and how many subscribers use mail apps with privacy protection, which can inflate or hide opens. Published averages mix all of these, so they say little about your own list. A more useful benchmark is your own open rate for the same segment and the same kind of email over the last few months. If that trend falls while clicks hold up, the cause is more likely in measurement than in the subject lines.
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