Open rate is the percentage of delivered emails that were opened by recipients.
In depth
Open rate is calculated as unique opens divided by delivered emails. It signals how well your sender name, subject line and preheader earn attention in the inbox. Average open rates run roughly 35 to 45 percent across industries, but the number has become less reliable since Apple introduced Mail Privacy Protection in 2021, which auto-loads tracking pixels and inflates recorded opens. For a cleaner measure of engagement, pair open rate with click-to-open rate. Improve open rate with strong subject lines, list segmentation, consistent sending reputation and good list hygiene.
Example
If 10,000 emails are delivered and 4,200 are opened, the open rate is 42 percent.
Related terms
See our full email marketing glossary or the complete email marketing guide.