What Is Email Open Rate?
Email open rate is one of the most fundamental metrics in email marketing. It measures the percentage of recipients who opened your email out of the total number who received it. A high open rate signals that your subject lines are compelling, your sender name is trusted, and your list is engaged with your brand.
The formula is straightforward: divide the number of emails opened by the number of emails delivered (not sent — bounced emails do not count), then multiply by 100 to get a percentage.
How to Calculate Email Open Rate
Formula: Email Open Rate (%) = (Emails Opened ÷ Emails Delivered) × 100
For example, if you sent a campaign to 2,000 subscribers, had 50 bounces (1,950 delivered), and 390 opens, your open rate = (390 ÷ 1,950) × 100 = 20%.
Note: Most email platforms track opens via a hidden 1x1 pixel image. Apple Mail Privacy Protection (MPP) can inflate open rates by pre-loading emails — keep this in mind when interpreting results.
Email Open Rate Benchmarks by Industry
- Government and Nonprofits: 25–40%
- Education: 22–28%
- Finance and Insurance: 20–25%
- Healthcare: 20–25%
- B2B Software/SaaS: 18–22%
- eCommerce / Retail: 15–20%
- Marketing and Advertising: 15–22%
A rate above 25% is generally excellent. Below 15% warrants investigation — your list may need cleaning or your subject lines need work.
Why Email Open Rate Matters
Open rate is the gateway metric for email marketing. If subscribers do not open your emails, nothing else matters — no clicks, no conversions, no revenue. Open rate also affects your sender reputation. Email service providers and inbox algorithms track engagement signals. Consistently low open rates can push future campaigns into spam folders.
5 Ways to Improve Your Email Open Rate
- Write better subject lines. Use curiosity, specificity, or urgency. A/B test two subject lines on a small segment before sending to the full list.
- Optimise your sender name. Emails from a person ("Mark from MarketingAI") tend to outperform generic company addresses.
- Segment your list. Sending targeted content to smaller, relevant segments dramatically outperforms blasting everyone.
- Send at the right time. Tuesday to Thursday mornings (8–10am in your audience's time zone) typically see the highest open rates.
- Clean your list regularly. Remove subscribers who have not opened an email in 6+ months. A smaller, engaged list outperforms a large, disengaged one.