Click-to-open rate
Lifecycle marketers use CTOR to separate message relevance from deliverability and list health.
Example scenario
A Klaviyo operator exports one promotional send’s engagement digest: eight thousand two hundred unique opens after Apple Mail Privacy Protection noise is filtered using the ESP’s machine-open suppression rules and one thousand two hundred forty unique clicks tied to link redirects in the same attribution window. Dividing clicks by opens yields a click-to-open rate near fifteen point one percent—creative leadership benchmarks that CTOR against last month’s hero banners before blaming inbox placement for revenue misses.
Click-to-open rate
Unique clicks / unique opens x 100
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How to calculate click-to-open rate (CTOR)
- Input unique clicks from your ESP’s campaign report—usually deduplicated recipients who clicked any tracked link once during the measurement window, excluding bot-filtered events your vendor flags.
- Input unique opens using the same send cohort and timestamp rule—prefer human-open definitions when Apple MPP inflates raw open pixels.
- Ensure clicks cannot exceed opens per recipient grain; if exports mix transactional plus marketing templates, narrow to one template ID before dividing.
- Read CTOR as unique clicks divided by unique opens; run template or hero-banner tests with stable segments so CTOR reflects creative rather than sudden audience remixes.
CTOR planning context (vertical and audience dependent)
- Retail/ecommerce promotional sends (house lists, broad benchmarks)
- CTOR frequently lands roughly ~10–18% when opens represent genuine human engagement
- Triggered replenishment or cart reminders versus batch newsletters
- Flows often sustain higher CTOR because intent and merchandise context align tightly with clicks
- Apple Mail Privacy Protection impact on open denominators
- Inflated open counts can artificially depress CTOR unless platforms suppress proxy opens or analysts pivot to clicks-per-delivered for Apple-heavy cohorts
Best use cases
- Forecasting and scenario planning
- Client education and pre-qualification
- Budget and performance decision support
Frequently asked questions
Why not just use click-through rate on delivered emails instead of CTOR?
CTR-on-delivered mixes inbox placement, subject-line pull, and creative relevance. CTOR isolates message and layout quality among people who already opened—useful when deliverability is stable but clicks stall because body content or offers missed.
My unique clicks exceed unique opens—can CTOR go above one hundred percent?
Not with consistent definitions: each recipient should count once per metric per send. Spikes usually mean opens came from a filtered cohort while clicks include forwarding, preview-bar artifacts, or mismatched export windows—reconcile timestamps before trusting CTOR.
Should SMS taps or push notifications enter the click numerator?
No unless your denominator counts opens from those channels. CTOR is email-native; omnichannel metrics need parallel KPIs so you do not blend incomparable populations.
Does excluding Apple privacy opens change which click count I should use?
Apply the same filtering philosophy to both numerator and denominator—if you drop proxy opens, keep clicks from the identical recipient universe and date range. Moving only the denominator without aligning clicks skews CTOR upward or downward artificially.
Glossary
Scenario modeling
Testing multiple assumptions to estimate possible outcomes before execution.
Commercial intent
User behavior indicating readiness to buy, subscribe, or request a quote.
Related calculators
Category: Email marketing analyticsTopics: Click-to-open rate (CTOR), Email engagement quality, Lifecycle optimization
Last reviewed: 2026-05-07
Reviewed by: Calclet Growth Team