ConversionMath

Click-to-Open Rate (CTOR) Calculator

Calculate click-to-open rate — the cleanest measure of how compelling your email content is to people who actually opened it.

Your CTOR

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Formula CTOR = (Unique Clicks ÷ Unique Opens) × 100

How to use this calculator

Enter the number of unique opens and the number of unique clicks your email received. The calculator returns your click-to-open rate. Use the "Calculate" selector to solve instead for clicks or opens implied by a given CTOR.

What is CTOR?

Click-to-open rate (CTOR) is the percentage of people who clicked a link after opening the email. It's calculated as unique clicks ÷ unique opens, and it isolates the quality of the email's content and offer from the strength of the subject line. While open rate reflects how well your subject line worked and click-through rate reflects overall campaign performance, CTOR specifically answers the question: "Once people opened this email, how many found something worth clicking?" High CTOR with low overall CTR usually means you have great content but a subject line or segment problem. Low CTOR with high opens usually means the subject line is overpromising or the content isn't delivering.

When to use this calculator

  • Evaluating the quality of email content and offers
  • Comparing creative variations after opens are controlled for
  • Diagnosing whether underperforming emails have a subject line problem or a content problem
  • Benchmarking how compelling your email body is
  • Reporting on content effectiveness to content teams

Frequently asked questions

What is a good click-to-open rate?
Across industries, CTOR typically averages 10–15%. Well-targeted B2B and niche campaigns can reach 20–30%. Promotional broadcast emails often land lower, around 6–10%. Welcome emails and post-purchase sequences frequently exceed 20% because the recipient has strong intent. Compare against your own historical CTOR rather than universal benchmarks — consistent segmentation and audience quality matter more than absolute numbers.

How is CTOR calculated?
CTOR = (Unique Clicks ÷ Unique Opens) × 100. If 200 of 1,250 opens resulted in a click, your CTOR is 16.00%.

What's the difference between CTOR and email CTR?
CTR measures clicks relative to emails delivered — a broad campaign performance metric. CTOR measures clicks relative to emails opened — isolating content quality from subject line performance. CTR tells you how the campaign did overall; CTOR tells you how the content did.

Why is CTOR affected by Apple Mail Privacy Protection?
Because it uses opens as the denominator. Apple Mail Privacy Protection inflates open counts by pre-fetching images, which means the denominator in CTOR is artificially high — pushing CTOR down. Post-iOS 15, many email marketers find their CTOR has dropped significantly without any real change in content performance. This is a measurement artifact, not a content problem. Some teams now focus on CTR (which is unaffected) rather than CTOR.

Should I use CTOR, CTR, or both?
Both, for different purposes. CTR is your primary performance metric — it reflects the full campaign. CTOR is useful for diagnosis — it tells you whether underperformance came from a weak subject line (low open rate) or weak content (low CTOR). Content and copy teams often focus on CTOR; audience and strategy teams focus on CTR.

How do I improve my CTOR?
Stronger CTAs, clearer offers, content that matches the subject line's promise, reducing distraction (one primary CTA beats many), better mobile formatting, and segmenting lists so the offer matches the recipient. Also: avoid overpromising in the subject line — it inflates opens without improving CTOR, creating a misleading performance signal.

What if my CTOR is very high?
Very high CTOR (30%+) usually indicates strong alignment between your subject line, audience, and content — the people opening are the right people, and the content is delivering on the promise. But it can also mean your subject line is undersized for your audience (only the most interested people open), and you might be leaving reach on the table with a bolder subject line that attracts a broader set of openers.

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