Understanding Email Open Rate
How we calculate. Open rate % = (opens ÷ delivered emails) × 100. See our methodology and accuracy policy .
Real-world scenario: A typical Email Open Rate case uses unique opens 2400 and delivered emails 10000. Enter the same figures below to reproduce the worked path.
What is Email Open Rate?
A top-of-funnel email KPI. Apple Mail Privacy and similar features can inflate opens—pair with clicks and conversions.
- Use delivered, not sent, when possible
- Unique opens beat total opens for rate math
- Subject and sender drive opens
The Formula
Worked Example
Common Use Cases
- Subject line tests: open lift
- List health: declining opens
- Newsletter reporting: period averages
Pro Tips
- Clean inactive subscribers
- Watch bot opens
- Prioritize click and revenue metrics
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Email Open Rate results are educational marketing planning aids—not guarantees of campaign performance. Platform definitions and attribution models vary.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
When to use this calculator
- Use this page when your wording matches email open rate and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about email open rate? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this email open rate calculator?
For email open rate, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for email open rate—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking email open rate, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For advertising and analytics definitions, consult:
- Google Ads Help — CPC, CPM, conversion, and ROAS concepts
- IAB — digital advertising standards
- Google Analytics Help — conversion and engagement metrics