CTR is calculated as (unique clicks ÷ successful deliveries) × 100. It is the most reliable engagement signal for email because it requires deliberate action — unlike open rate, machine prefetching does not affect it.
Some platforms report 'click-to-open rate' (CTOR), which is clicks ÷ opens. CTOR isolates content performance from subject-line performance: a high CTOR with a low open rate means your subject line is the bottleneck.
Average CTRs cluster around 2–5% across industries, with transactional and highly-segmented campaigns reaching 10%+. Improvements typically come from better segmentation, clearer single calls to action, and link tracking that lets you see which sections of the email pull the most clicks.