The share of delivered emails that were opened, with every step shown.
Open rate
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Enter the number of emails sent and unique opens to see the rate.
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Enter the number of emails sent, the bounces and the unique opens from your email tool’s report. The calculator gives the open rate on delivered emails, rounded to two decimal places, with the workings. The optional panels add total opens, take out machine opens and emails sent without open tracking, or compare with another send, such as version B of an A/B test.
Emails sent is the number of recipients. Bounces are the emails the receiving server refused, for good (hard bounces) or for now (soft bounces). Unique opens count the people who opened the email at least once; total opens count every opening. Mailchimp, for one, divides unique opens by delivered emails, so enter the bounces to get the same rate.
An open is recorded when the email loads a tiny invisible image, the tracking pixel. Someone who reads with images turned off is not counted unless they click a link, which Mailchimp counts as an open when click tracking is on. And some opens are not people at all: Apple Mail Privacy Protection (MPP) preloads the pixel even when the email is not opened, and security scanners open emails to check them.
If your tool reports machine opens, enter them; enter too any delivered emails sent without a tracking pixel, for example to people who refused tracking. The calculator then gives the measurable open rate. Those recipients leave both sides of the division, because nobody knows whether they read the email. Taking out machine opens lowers the rate; taking out untracked emails raises it, since those emails could never record an open through the pixel.
Enter the delivered emails and unique opens of the other send to get the difference in percentage points and the relative change. They say different things: from 20% to 25%, the rate gains 5 percentage points, a rise of 25%. Compare sends measured the same way, with or without machine opens on both sides.
Rates are rounded to the nearest hundredth of a percentage point, halves away from zero, and opens per opener to two decimal places. The delivery rate is 100 minus the bounce rate as shown, so the two always add up to 100%. The difference and the relative change (to one decimal place) start from the rates as shown, so every line of the workings checks by hand.
Delivered = sent − bounced.
Open rate = unique opens ÷ delivered × 100.
Bounce rate = bounced ÷ sent × 100; delivery rate = 100 − bounce rate.
Opens per opener = total opens ÷ unique opens.
Measurable open rate = (unique opens − machine opens) ÷ (delivered − untracked − machine opens) × 100.
Difference (percentage points) = open rate − other send’s rate; relative change = difference ÷ other send’s rate × 100.
A newsletter goes to 10,000 subscribers and 200 emails bounce, so 9,800 are delivered: a bounce rate of 2% and a delivery rate of 98%. The report shows 2,450 unique opens: 2,450 ÷ 9,800 × 100 = 25%, and 7,350 delivered emails were not opened. With 3,920 total opens, each opener opened it 1.6 times on average. The tool flags 900 of the opens as Apple Mail Privacy Protection opens: without them, 1,550 opens from 8,900 measurable emails give a measurable open rate of 17.42%. Last month’s newsletter had 1,900 unique opens from 9,500 delivered emails, or 20%: this one gained 5 percentage points, a rise of 25%.
Divide unique opens by delivered emails and multiply by 100: 1,200 unique opens from 4,800 delivered emails give 1,200 ÷ 4,800 × 100 = 25%. Delivered emails are the emails sent minus the bounces.
By delivered emails, as Mailchimp does: it defines the open rate as the percentage of successful deliveries that were opened. Dividing by emails sent gives a slightly lower rate, because a bounced email could never be opened. If you do not know the bounces, the calculator works on the emails sent and says so.
Unique opens count people: someone who opens the same email three times counts once. Total opens count every opening, so they are never fewer than unique opens. The open rate uses unique opens, and total opens ÷ unique opens tells you how often each opener came back.
Yes. Mailchimp explains that when a contact turns it on, Apple Mail preloads the tracking pixel even if the email is never opened, so the email is reported as opened. Security scanners do the same. If your tool reports these machine opens, enter them in the optional panel to get the measurable open rate. Mailchimp also suggests watching other measures, such as bounces, unsubscribes and conversions.
It can be needed. Regulation 6 of the Privacy and Electronic Communications Regulations (PECR), as it reads since 5 February 2026, bars storing or reading information on a person’s device unless an exception in Schedule A1 applies, consent being one of them. The ICO’s guidance on storage and access technologies, last updated on 29 April 2026, uses a marketing email with a tracking pixel as an example: where the pixel stores or reads information on the reader’s device, regulation 6 applies. Read the guidance before you rely on open tracking. Emails sent without a pixel go in ‘Delivered emails without open tracking’, so they do not drag the rate down.
No official body publishes a benchmark. Sending tools publish their own averages, but they vary by sector, list and tool, and they may include machine opens. The surest yardstick is your own past sends, measured the same way.
This calculator gives general information, not legal, tax, financial or accounting advice. Whether you may track email opens depends on your case: read the ICO’s guidance or ask a data protection adviser.
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