Open Rate / Analytics Terms Open Rate Open rate is an email marketing metric that measures the percentage of recipients who open a specific email campaign. It is calculated by dividing the number of unique opens by the number of delivered emails and then multiplying by 100. Open rate gives insight into how well your subject line, sender name and send time resonate with your audience, and it is often used as an early indicator of campaign engagement. For example, if you send an email to 1,000 people and 200 of them open it, your open rate is 20 percent. High open rates suggest that your message was compelling enough to catch attention, while low open rates may signal issues such as poor timing, irrelevant content or inbox placement problems. Subject lines, preview text and sender reputation all influence whether a recipient chooses to open an email. While open rate remains a valuable metric, it is not always completely accurate. Privacy updates in email clients like Apple Mail can artificially inflate open rates by preloading tracking pixels. For this reason, open rate should be interpreted alongside other metrics such as click-through rate, conversion rate and unsubscribe rate. For nonprofits, a strong open rate can indicate donor interest or volunteer engagement. For B2B and SaaS brands, it helps measure the effectiveness of lead nurturing and product updates. Continual testing and audience segmentation can improve open rate performance over time.