Email Open Rate Calculator
Measure an email campaign properly: open rate (subject line performance), click rate (overall campaign performance) and CTOR — clicks among openers, which isolates how well the content itself converted attention.
How to use this calculator
- Enter emails sent and bounced — rates are computed on delivered, not sent.
- Enter unique opens (not total opens) and optionally unique clicks.
- Read CTOR for content performance and open rate for subject-line performance.
Formula used
Delivered = sent − bounced. The three metrics diagnose different stages: open rate = subject line + sender reputation; CTOR = content and call-to-action; click rate = the whole chain multiplied together.
Example calculation
10,000 sent, 200 bounced, 2,450 opens, 320 clicks: delivery 98%, open rate = 2,450 ÷ 9,800 = 25%, click rate 3.3%, CTOR = 320 ÷ 2,450 = 13.1%.
Diagnosis: subject line at benchmark, content slightly above it — the campaign's a healthy baseline to beat.
Reading email metrics after the privacy era
The metric trio splits the funnel cleanly: a low open rate with high CTOR means great content behind a weak subject line; the reverse means clickbait subjects writing checks the content can't cash. Optimizing the right stage is the entire craft.
Since 2021, Apple's Mail Privacy Protection pre-fetches emails and fires opens automatically — inflating open rates by 10–20 points for Apple-heavy lists and making them unreliable for A/B decisions. Clicks and conversions survived the change intact, which is why modern email programs anchor on them and treat opens as a soft signal.
Why use this calculator?
- Compute on delivered (not sent) — the mistake that flatters bad lists.
- Separate subject-line problems from content problems via CTOR.
- Catch list-hygiene issues with the bounce-rate warning.
Frequently asked questions
What is a good email open rate?
20–25% is a typical cross-industry range, with newsletters to engaged audiences reaching 35–45%. Post-2021 numbers are inflated by Apple's auto-opens, so compare only within your own list and era.
What is CTOR and why track it?
Click-to-open rate = clicks ÷ opens — how well your content converted the people who actually looked. It isolates content quality from subject-line quality; 10–15% is a common healthy range.
How do I improve deliverability?
Keep bounces under ~2% by pruning invalid addresses, authenticate (SPF, DKIM, DMARC), sunset chronically unengaged subscribers, and earn engagement — mailbox providers route senders people ignore toward spam.