---
title: "Open rate: definition, formula and example"
url: "https://coldmeetings.com/glossary/open-rate.md"
canonical_url: "https://coldmeetings.com/glossary/open-rate"
last_updated: "2026-10-19"
type: "conceptual"
summary: "Open rate is the percentage of delivered emails that registered an open. Learn the formula, see a worked example and why opens are a weak signal."
related: ["https://coldmeetings.com/glossary/reply-rate.md", "https://coldmeetings.com/glossary/bounce-rate.md", "https://coldmeetings.com/glossary/a-b-testing.md"]
---

# Open rate: definition, formula and example

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Open rate is the percentage of delivered emails that registered an open. Learn the formula, see a worked example and why opens are a weak signal.

**What is open rate?**

Open rate is the percentage of delivered emails that registered an open. It is measured by a tiny hidden image that loads when a message is displayed, so it counts loads rather than people reading.

Group: 5. Pipeline measures.

## Open rate

- open rate = opened / delivered x 100

## The parts

1. **Opened**: The number of messages where the tracking image loaded. One person opening a message three times is usually counted once.
2. **Delivered**: Messages that reached an inbox, which is sent minus bounced. Dividing by delivered rather than sent keeps bad addresses out of the rate.
3. **A weak signal**: Some mail apps load images automatically, so an open can be recorded when no one read the message. Some readers block images, so a real read can go uncounted.
4. **Best used as a trend**: A sudden drop across many sends is worth a look. A small difference between two sends is not a reason to act.

## Worked example: one send at a payments company

Ledgerlane Payments, a fictional company, delivers a message to 480 prospects. The tracking image loads 168 times.

1. Opened: 168. Delivered: 480.
2. Open rate: 168 / 480 x 100 = 35%.
3. The company reads this number next to reply rate, because replies show that a person acted.

One send, as a share of delivered messages

- Open rate: 35%
- Not opened: 65%

## How to apply it

1. Count opens against delivered messages, not sent ones.
2. Compare the rate with your own earlier sends instead of an outside number.
3. Read it together with reply rate and meetings booked.
4. Use a drop across many sends as a reason to check subject lines and inbox placement.

## Common mistakes

- Treating an open as proof that a person read the message.
- Judging a test by a small difference in open rate.
- Optimizing opens at the cost of the replies and meetings you actually want.

## Related terms

- [Reply rate](https://coldmeetings.com/glossary/reply-rate.md): Reply rate is the portion of delivered emails answered by the recipient.
- [Bounce rate](https://coldmeetings.com/glossary/bounce-rate.md): Bounce rate is the portion of the emails you sent that came back undelivered.
- [A/B testing](https://coldmeetings.com/glossary/a-b-testing.md): A/B testing sends two versions of a message, differing in one element, to similar groups at the same time to see which version gets the better result.

## Keep reading

- [Cold email metrics](https://coldmeetings.com/blog/cold-email-metrics.md)
- [Cold email subject lines](https://coldmeetings.com/blog/cold-email-subject-lines.md)
- [Cost per meeting calculator](https://coldmeetings.com/tools/cost-per-meeting.md)

## Questions

### How do you calculate open rate?

Divide the number of opened messages by the number delivered and multiply by 100.

### Is open rate accurate?

Not fully. Image loading can happen without a person reading, and image blocking can hide real reads, so use it as a rough signal.

### Is a high open rate a good result?

It suggests the subject line and sender were noticed, but replies and meetings are the results that matter.

### Why divide by delivered and not sent?

Bounced messages never had a chance to be opened, so counting them lowers the rate for a reason unrelated to your message.

Questions about outbound for your own company? Email hello@coldmeetings.com.

## Related

- [Reply rate: definition, formula and example](https://coldmeetings.com/glossary/reply-rate.md)
- [Bounce rate: definition, formula and example](https://coldmeetings.com/glossary/bounce-rate.md)
- [A/B testing: definition, method and example](https://coldmeetings.com/glossary/a-b-testing.md)