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Metrics & engagement

Open rate

Definition

Open rate is the percentage of delivered emails that recipients opened, calculated as unique opens divided by delivered messages — a headline gauge of subject-line appeal and sender trust.

How open rate is calculated

Open rate = unique opens ÷ emails delivered × 100. An open is registered when the recipient's client loads a tiny tracking pixel embedded in the message. It's usually counted on unique opens (one per recipient) rather than total opens.

Because it depends on images loading, open rate has always been an estimate — and recent privacy features have made it noisier still.

What affects open rate

  • Subject line and preview text — the first thing recipients judge
  • Sender name and trust — a recognised From line gets opened
  • Send time and frequency relative to your audience's habits
  • Deliverability — mail in the spam folder can't be opened
  • List engagement — a well-maintained list opens far more

The privacy caveat

Apple Mail Privacy Protection and similar features pre-load tracking pixels, inflating open counts with 'opens' that never happened. Treat open rate as a directional trend, not an exact figure — and lean on clicks and conversions for hard measurement.

Frequently asked questions

What's a good email open rate?

It varies widely by industry, but many senders see 20–40% on engaged lists. Compare against your own history and your sector rather than a universal number.

Why did my open rate suddenly jump?

Often Apple Mail Privacy Protection auto-loading pixels, which counts as opens. A jump without a matching rise in clicks usually means inflated open tracking, not real engagement.

Is open rate still worth tracking?

As a trend, yes — but pair it with click rate and conversions, which are far harder to fake and reflect genuine interest.

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What Is Email Open Rate? Formula & Benchmarks — Climails