Email Marketing Calculator
Open rate, click rate, click-to-open and unsubscribe rate from one send — with the caveat about opens.
Four rates describe a send.
How the email marketing calculator works
Four rates describe a send. Open rate is opens over delivered; click rate is clicks over delivered; click-to-open is clicks over opens, which measures the content rather than the subject line; unsubscribe rate is the cost of sending.
One caveat matters more than the arithmetic. Since Apple's Mail Privacy Protection in 2021, opens are pre-fetched automatically for a large share of recipients whether or not anyone read the message. Open rates rose across the industry without any change in behaviour, and they are no longer a reliable measure. Click rate and click-to-open are what survived.
Delivered is sent minus bounces, and using sent instead understates every rate.
Formula: open rate = opens/delivered; CTOR = clicks/opens
Worked examples
| Inputs | Click rate | Note |
|---|---|---|
| 50,000 sent, 12,000 opens, 1,800 clicks | 3.655% | 3.66% click rate, 15% CTOR |
| A small engaged list | 13.568% | 30% CTOR |
| A bad send | 0.196% | high bounce and unsubscribe |
FAQFrequently asked questions
How do I calculate email open rate?
Unique opens divided by delivered emails — sent minus bounces, not sent.
Why are open rates unreliable now?
Apple Mail Privacy Protection pre-fetches images for many recipients, registering an open whether or not anyone read it. Rates jumped industry-wide in 2021 with no behaviour change.
What is click-to-open rate?
Clicks divided by opens. It measures the message content rather than the subject line, and it is the more stable figure.
What is a good click rate?
Broadly 2% to 5% for a general list, higher for small engaged ones. Compare against your own history.
What unsubscribe rate is a problem?
Above about 0.5% per send is worth investigating — usually frequency, relevance or how the list was built.
Where these figures come from
- Interactive Advertising Bureau — measurement guidelines — the impression and viewability definitions CPM depends on
- Australian Competition and Consumer Commission — the Australian consumer law regulator
Last checked: September 2026. These are standard industry definitions; where platforms disagree, the page says so.