What is open rate in email marketing?

Open rate is the share of delivered emails that a recipient opened. It divides unique opens by emails delivered — deliberately not by emails sent, because bounced messages never reached an inbox and could not have been opened. Counting them would penalise you for a stale list rather than tell you anything about the email itself.

How do you calculate email open rate?

Open rate (%) = (unique opens ÷ emails delivered) × 100. For example, 1,000 opens on 5,000 delivered emails is 20.0 %. Unique means each recipient counts once, however many times they open the message.

What is a good open rate?

As a rough guide, under 15 % is low, 15–25 % is solid and above 25 % is strong. These are MPP-adjusted figures; benchmark reports quoting 30–44 % are counting machine opens. B2B newsletters, triggered mail and transactional email typically run well above the general range.

Why is open rate unreliable since Apple Mail Privacy Protection?

Apple Mail Privacy Protection preloads tracking pixels whether or not the recipient actually reads the email, so those loads are recorded as opens. Depending on your audience, 40 to 70 % of reported opens can come from MPP rather than from people. Open rate should therefore never be your only KPI — read it alongside click rate and conversion rate.

Email Open Rate Calculator

Calculate the open rate of your newsletter and see where it sits against industry benchmarks.

Emails delivered Delivered, not sent — bounces are excluded Unique opens Each recipient counted once, however often they open

Open rate

20.0 %

(unique opens ÷ emails delivered) × 100

Where your open rate sits

15 % 20 % 25 %

< 15 % (Low) 20 % (Solid) > 25 % (Strong)

Next step

Email Click Rate Calculator

An open is attention; a click is interest. Machine opens cannot fake the second one.

Delivered, not sent: the open rate formula turns on its denominator

Your email open rate is the share of delivered emails that someone actually opened. Everything worth arguing about sits in the denominator. A bounced message never reached an inbox, so it could not have been opened — leaving those in the divisor would drag every campaign down by however much of your list has gone stale, which tells you nothing about the email you wrote. Mailchimp, ActiveCampaign and Salesforce all divide by delivered, and so does this calculator. Several free tools divide by sent instead and will report a lower number for the very same campaign.

Open rate (%) = (unique opens ÷ emails delivered) × 100

How to calculate open rate when 500 of 5,500 emails bounce

A newsletter goes out to 5,500 addresses and 500 of them bounce. Of the 5,000 that were delivered, 1,000 get opened:

Emails delivered5,000

Unique opens1,000

Open rate = (1,000 ÷ 5,000) × 100 = 20.0 %

Put the same campaign through a calculator that divides by sent and you get 18.2 %, because the 500 bounces stay in the divisor. Neither figure is bad arithmetic — they answer different questions. This one answers the question worth asking: of the people who could have opened it, how many did?

The average email open rate you see quoted is inflated

The figures below are MPP-adjusted — real human opens. The 30–44 % averages that circulate in benchmark reports are inflated by Apple Mail Privacy Protection, which preloads tracking pixels whether or not anyone reads the message (see the box further down). Your own sector shifts the bar as well: B2B newsletters, triggered mail and confirmed opt-in lists all sit meaningfully higher.

Low < 15 %

Solid 15–25 %

Strong > 25 %

The subject line is only half of it: how to improve email open rate

Subject line and preheader: Short lines with a concrete benefit or a personal hook move the number more directly than anything else you can change. The preheader — roughly 80 to 100 characters — is the second lever, and most senders leave it on autopilot.
Send time: Test days and hours instead of inheriting someone else's rule. Tuesday to Thursday between 9 and 11 am works for a lot of B2B lists, but your own results beat any rule of thumb.
List hygiene and segmentation: Inactive subscribers pull the average down and damage your sender reputation, which then costs you deliverability on top. Re-engagement campaigns and pruning dead contacts fix the metric for good rather than for one send.
Sender name: Mail from a recognisable person opens more often than mail from a company mailbox nobody pictures.

Apple Mail Privacy Protection counts opens that never happened

Since Apple Mail Privacy Protection (MPP) shipped, tracking pixels are preloaded whether or not the message is ever read. That inflates open rates, and not by a rounding error: depending on your audience, 40–70 % of reported opens can be MPP rather than people. Open rate on its own stopped being a trustworthy KPI that day — always read it next to your click and conversion rate.

Background and sources

Open rates have been unreliable and inflated since Apple MPP, so the figures above are the conservative, adjusted ones. Click-through rate and click-to-open rate carry far more signal — see the click rate calculator.

Mailchimp — Email Marketing Benchmarks (large ESP dataset, with an explicit MPP caveat)
MailerLite — Email Marketing Benchmarks (3.6 million campaigns analysed)

Frequently asked questions

What is open rate in email marketing?: Open rate is the share of delivered emails that a recipient opened. It divides unique opens by emails delivered — deliberately not by emails sent, because bounced messages never reached an inbox and could not have been opened. Counting them would penalise you for a stale list rather than tell you anything about the email itself.
How do you calculate email open rate?: Open rate (%) = (unique opens ÷ emails delivered) × 100. For example, 1,000 opens on 5,000 delivered emails is 20.0 %. Unique means each recipient counts once, however many times they open the message.
What is a good open rate?: As a rough guide, under 15 % is low, 15–25 % is solid and above 25 % is strong. These are MPP-adjusted figures; benchmark reports quoting 30–44 % are counting machine opens. B2B newsletters, triggered mail and transactional email typically run well above the general range.
Why is open rate unreliable since Apple Mail Privacy Protection?: Apple Mail Privacy Protection preloads tracking pixels whether or not the recipient actually reads the email, so those loads are recorded as opens. Depending on your audience, 40 to 70 % of reported opens can come from MPP rather than from people. Open rate should therefore never be your only KPI — read it alongside click rate and conversion rate.