---
title: A/B subject line tests
description: Send two subject lines to different halves of your audience in one campaign, and read which one was opened and clicked more.
url: "https://hiveplugins.com/docs/hive-mail-ab-subject-tests/"
updated: "2026-10-28"
category: Hive Mail
---

# A/B subject line tests

An A/B test sends two subject lines in one campaign. Each person gets one of them, and the report shows which was opened and clicked more. Only the subject changes; the email is the same for everyone. You need a draft campaign: see [How to create and send a campaign](/docs/hive-mail-create-and-send-a-campaign/).

## Set up the test

1. On the **Setup** step, type the first subject in **Subject line A** (the label is **Subject line** until you turn the test on).
2. Tick **Test a second subject line (A/B)**.
3. Type **Subject line B**.
4. Move the slider under **Who gets which** ("A 50%" / "B 50%"). It goes from 10 to 90 percent in steps of 5.
5. Check the **Inbox preview** card, which now shows both subjects, then click **Continue to audience**.

![Step 1 with the A/B box ticked, subject line B filled in and the slider at 70 and 30](https://hiveplugins.com/wp-content/uploads/2026/10/hivemail-campaigns-ab-setup-04.webp)

To preview or test both, use the **Subject A** / **Subject B** switch on the card **The email** in **Review and send**, and choose the **Subject line** in **Send a test**.

Each person gets exactly one subject, chosen by a fixed rule from the campaign and the contact, so a person always gets the same one. The split applies to the whole audience at once. Hive Mail does not pick a winner or send the better subject to the rest later.

## Checklist lines

| Level | Text |
| --- | --- |
| Red | "Write the second subject line for the A/B test, or switch the test off." |
| Orange | "Both subject lines are the same, so the test cannot tell them apart." |
| Green | "A/B test: {a}% get subject A, {b}% subject B." |

A split outside 10 to 90 shows "The split must be between 10 and 90 percent."

## Read the result

After sending, the card **A/B subject lines** has one row per subject:

| Column | Meaning |
| --- | --- |
| **Subject** | The letter and the subject line |
| **Sent** | How many people got this version |
| **Opened** | Open rate, with the number of people |
| **Clicked** | Click rate |

A green **Best** badge marks the highest open rate, only with two subjects and a rate above 0. The card **People** has a **Subject** column showing A or B. See [How to read a campaign report](/docs/hive-mail-read-a-campaign-report/).

![The A/B subject lines table in a campaign report with the Best badge on subject B](https://hiveplugins.com/wp-content/uploads/2026/10/hivemail-campaigns-ab-report-05.webp)

> **Tip:** Open rates are a guide: Apple Mail privacy protection and security scanners affect them, and small lists give weak answers. Use clicks as a second signal. See [Email tracking](/docs/hive-mail-email-tracking-opens-and-clicks/).

Next: [How to read a campaign report](/docs/hive-mail-read-a-campaign-report/), [Merge tags and fallbacks](/docs/hive-mail-merge-tags-and-fallbacks/).