Open ratio
Open ratio, also called open rate, is the percentage of successfully delivered emails that recipients opened, calculated by dividing the number of recorded opens by the number of emails delivered and multiplying by 100.
It has traditionally been one of the most widely reported email marketing metrics, providing a quick read on how well a subject line and sender name are performing and how engaged a list is with a particular sender.
Open ratio is useful for comparing performance between campaigns, tracking engagement trends over time, and identifying lists or segments that are becoming disengaged. A significant drop in open ratio across consecutive sends is often an early warning signal worth investigating before it becomes a deliverability problem. Equally, a campaign that achieves an unusually high open ratio is worth analysing to understand what drove it and whether those elements can be replicated.
The reliability of open rates as a precise metric has diminished in recent years, primarily due to Apple Mail Privacy Protection, which preloads email content, including tracking pixels, via Apple’s servers. This means opens are recorded even if the recipient didn’t view the email, inflating reported open rates for senders with significant Apple Mail audiences. Most practitioners now treat open ratio as a directional indicator rather than an exact measure, and place greater weight on click rate and conversion rate as the primary signals of genuine engagement.
What is a good open ratio for email marketing?
Benchmarks vary considerably by industry, email type, list size, and audience. Generally, open rates between 20% and 40% are considered healthy for marketing emails, with transactional and triggered emails typically achieving higher rates than broadcast campaigns. The most meaningful benchmark is your own historical performance: consistent improvement over time matters more than hitting an industry average. Bear in mind that Apple Mail Privacy Protection has inflated open rate figures for many senders since 2021, so comparing current rates to pre-2021 benchmarks requires some caution.
What is the difference between open ratio and click-to-open ratio?
Open ratio measures the percentage of delivered emails that were opened. Click-to-open ratio (CTOR) measures the percentage of opened emails in which at least one link was clicked. Open ratio reflects subject line and sender name performance; CTOR reflects how compelling the email’s body content and call to action were for the people who actually opened it. Used together, they help pinpoint where an email is losing its audience: a low open ratio points to a subject line or sender name issue, while a low CTOR with a healthy open ratio points to a content or offer problem.
How can I improve my email open ratio?
The most direct lever is the subject line: testing different approaches, lengths, levels of specificity, and personalisation consistently produces measurable improvements. Sender name also matters: recipients are more likely to open emails from names they recognise and trust. Send timing plays a role, too: emails sent when recipients are most likely to be actively checking their inboxes tend to perform better. List hygiene is the foundation: removing inactive and invalid contacts keeps your engaged audience as the dominant proportion of your list, naturally improving your open rate over time.