Related Calculators
Open Rate = (Opens ÷ Delivered) × 100
Use this free, online email open rate calculator to calculate your open rate instantly. It works as a general open rate calculator and email marketing calculator too. Just enter any two known values (opens, delivered, or rate) and it solves for the third.
What Is Email Open Rate?
Email open rate is the percentage of successfully delivered emails that were opened by the recipient. It’s traditionally used to judge subject line performance, but its accuracy has become genuinely unreliable since Apple Mail Privacy Protection began pre-fetching images in 2021, inflating open rates for a large share of recipients regardless of whether they actually looked at the email.
Why Open Rate Numbers Are Inflated (Read This Before Trusting Any Benchmark)
This is the single most important thing to understand about email open rate in 2026, and most calculators don’t mention it at all.
Apple Mail Privacy Protection (MPP) automatically pre-loads images, including the invisible tracking pixel used to register an “open,” for a large share of Apple Mail users. This happens whether or not the person actually looked at the email. Since Apple Mail represents a substantial share of most inboxes, this quietly inflates open rate data across the entire industry, not just for individual senders.
What this means practically:
- Treat your open rate as a directional trend, not a precise number. A rise or fall over time is still meaningful; the absolute figure is not as trustworthy as it was before 2021.
- Click rate, click-to-open rate, and conversions are more reliable signals than open rate alone, since they require a genuine action rather than a pre-fetched image load.
- Every benchmark figure below inherits this same inflation, since it’s measured the same way industry-wide — so the numbers are still useful for relative comparison, just not as an absolute truth.
How to Calculate Email Open Rate
To calculate open rate, divide opens by the number of emails successfully delivered, then multiply by 100.
Open Rate = (Opens ÷ Delivered) × 100
Email Open Rate Formula, Step by Step
- Find your total opens for the campaign you’re measuring
- Find your total delivered emails (sent minus bounces) for the same campaign
- Divide opens by delivered
- Multiply by 100 to get a percentage
Worked Examples
- Small campaign: 250 opens, 1,000 delivered 250 ÷ 1,000 × 100 = 25% open rate
- Mid-size campaign: 3,800 opens, 14,500 delivered 3,800 ÷ 14,500 × 100 = 26.2% open rate
- Agency-scale account: 42,000 opens, 165,000 delivered 42,000 ÷ 165,000 × 100 = 25.45% open rate
Open Rate Calculator Formula (Reverse Calculation)
Because this is a reverse-capable calculator, you can also start from a target open rate and solve for opens or delivered emails instead.
- To find Opens: Opens = (Open Rate ÷ 100) × Delivered
- To find Delivered: Delivered = Opens ÷ (Open Rate ÷ 100)
What Is a Good Email Open Rate?
Reported “average” open rates vary substantially by platform, since each measures a different customer base with different list quality and campaign types. And all of them carry the Apple MPP inflation described above.
|
Context |
Typical Open Rate |
Source |
|---|---|---|
|
All-industry blended average |
21.5% – 42% |
Mailchimp, Klaviyo, ActiveCampaign, CO Consulting (2026) — wide spread reflects different measured populations |
|
Klaviyo, all-vertical campaigns (183,000+ senders) |
~31% |
Klaviyo (2026) |
|
Mailchimp, all users |
~35.6% |
Mailchimp (2026) |
|
ActiveCampaign, customer campaigns |
~39.3% |
ActiveCampaign (2025) |
|
Government & nonprofits (highest industry) |
~28.7% |
Mailchimp (2026) |
|
Automated welcome/flow emails (vs. regular campaigns) |
40% – 60% |
Klaviyo (2026) automated flows consistently outperform one-off campaigns |
|
Top 10% of senders |
45.1%+ |
Klaviyo (2026) |
Why the range is wide: don’t average these figures together, each platform measures its own customer mix, campaign definitions, and Apple MPP exposure differently. Compare your open rate against your own historical baseline and, ideally, against the specific platform you use, since Klaviyo’s ecommerce-heavy customer base and Mailchimp’s broader mix genuinely aren’t measuring the same population.
How to Improve Your Email Open Rate
- Write specific, curiosity-driven subject lines rather than generic ones, specificity consistently outperforms vague headlines
- Clean your email list regularly to remove inactive subscribers, which drags down both open rate and sender reputation
- Test send times, open rates vary meaningfully by day of week and time of day for the same list
- Warm up new sending domains gradually to build sender reputation before high-volume sends
- Lean on automated flows (welcome series, abandoned cart) where possible. They outperform one-off campaigns by a wide margin
- Track click rate and click-to-open rate alongside open rate, since they’re far less affected by Apple MPP inflation