Open rate is the metric that marketers use to measure the number of people who opened an email compared to the number of people who received the email.

A higher open rate means more of your recipients opened the email.

To improve your open rates, look at the campaigns you have send with the highest open rates — do they have anything in common? It could be a technique you've used with writing an effective subject line, or a specific time of the day you sent the email out at.

If you're struggling with subject line ideas, try our free AI Subject Line Generator to spark some inspiration.

Why open rate can be unreliable as a metric

Open rate has become less reliable over time for a variety of reasons.

Critically, changes to email platforms and an increased focus on privacy, mean more inbox providers are implementing techniques to make it harder to track opens.

Digital marketing consultancy Econsultancy has a good summary of the reasons why marketers should approach open rates with caution.