Click-to-Open Rate Calculator
Click-to-open rate (CTOR) measures what percentage of people who opened your email actually clicked a link. It is a purer measure of content quality than raw click-through rate because it removes the variable of how many people saw your subject line. If your CTOR is low even when opens are high, the problem is your email content or call to action, not your subject line. Enter unique opens and unique clicks from your email platform's campaign report to calculate CTOR.
CTOR formula
CTOR = Unique Clicks / Unique Opens * 100
Use unique clicks and unique opens (not total clicks/opens) to avoid counting the same person multiple times and to accurately measure engagement per reader.
CTOR vs CTR: which to use?
- Use CTR to evaluate overall campaign performance and compare campaigns with similar list sizes.
- Use CTOR when diagnosing content problems: if opens are healthy but CTOR is low, the subject line works but the body copy or CTA does not.
- A/B test body copy and CTA button text using CTOR as the primary metric.
- Segment CTOR by list (customers vs prospects, engaged vs unengaged) for actionable insights.
Click-to-open rate: frequently asked questions
What is click-to-open rate (CTOR)?
CTOR is the percentage of people who opened your email and then clicked a link within it. It is calculated as unique clicks divided by unique opens. CTOR isolates the effectiveness of your email content and call to action, separate from subject line performance.
How is CTOR different from click-through rate (CTR)?
CTR divides clicks by total emails sent (or delivered). CTOR divides clicks by emails opened. CTOR measures content quality among engaged readers, while CTR measures overall campaign performance including those who never opened.
What is a good CTOR for email marketing?
CTOR benchmarks vary by industry. Broadly, 10 to 20% is considered a healthy range for marketing emails. Transactional emails (receipts, shipping notifications) often see 20 to 40% CTOR. Segment by email type when comparing.
How can I improve CTOR?
Improve content relevance by segmenting your list and personalizing offers. Use a single, clear call to action rather than multiple competing links. Place the most important CTA above the fold. Test button vs text link CTAs. Make the email preview of the CTA visible on mobile.
Does CTOR account for Apple Mail Privacy Protection?
No. Apple Mail Privacy Protection (MPP) artificially inflates open counts by pre-loading email content. This deflates CTOR for lists with high Apple Mail usage. Monitor CTOR trends over time rather than relying on absolute values, and segment Apple Mail opens separately if possible.
Official sources
- Federal Trade Commission, CAN-SPAM Act: ftc.gov CAN-SPAM Guide.
- U.S. Census Bureau, E-Stats: census.gov/programs-surveys/e-stats.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.