100% Private & Secure

MBOX Email Counter
Count Emails Instantly

Drop an .mbox file to count emails. Large number, file info, and average email size — no upload.

Instant email countFile size analysisAverage email sizeWorks with any MBOX

Drop your .mbox file here

or click to browse

Overview

What Is the MBOX Email Counter?

The MBOX Email Counter is a free online tool that counts how many emails are in an MBOX file. MBOX stores many messages in one file, separated by lines starting with "From ". The tool counts those separator lines and shows a large count number plus file name, size, processing time, and average email size — all without uploading your file.

No upload is required — your data stays completely private. Use it to verify Thunderbird or Gmail exports, plan migrations, or get a quick count for compliance or capacity planning.

The count is displayed with an animated counter that counts up to the final number. The result card shows file details and average email size (file size ÷ count) for a clean, minimal view focused on the result.

Features

Features of the MBOX Email Counter

Count MBOX emails with a clear, minimal UI

Instant count

Counts lines starting with 'From ' (the MBOX separator) and shows the total number of emails.

Big number display

A large, prominent count in the center with an animated counter that counts up to the result.

File info

Shows file name, file size, processing time, and average email size (file size ÷ count).

Fast processing

Reads the file and counts separators instantly — no waiting, no uploading.

No upload

Your MBOX file is never uploaded. Your data stays completely private.

Private & secure

Your mailbox file never leaves your device. Ideal for quick counts on sensitive exports.

How it works

How to Count Emails in an MBOX File

Four simple steps — no install, no sign-up

01
01

Open the MBOX Counter

Go to the MBOX Email Counter page and you'll see the upload area.

02
02

Drop your .mbox file

Drag and drop an .mbox file (e.g. from Thunderbird or Gmail export), or click to browse.

03
03

See the count

The tool counts lines starting with 'From ' and shows the total in a large animated number.

04
04

Review details

Check file name, size, processing time, and average email size in the info card below.

Use cases

Use Cases for the MBOX Email Counter

When and why to count MBOX emails online

Thunderbird export

Quickly see how many emails are in a Thunderbird MBOX folder before migrating or archiving.

Gmail Takeout

Count emails in MBOX files from Google Takeout to verify export completeness.

Migration planning

Know exactly how many messages you're moving before starting a migration.

Compliance & audit

Get a quick email count for archives without opening or uploading full content.

Average size

Use file size ÷ count to see average email size for capacity planning.

Developer & QA

Verify MBOX generation in scripts or apps by checking the expected email count.

Compare Plans

Free vs Paid — MBOX Counter

Get started free, upgrade when you need more power.

Feature
Free
Paid
Daily usage
5 uses/day
Unlimited
File size limit
10 MB
Up to 500 MB
All core features
No software installation
Works on any device
Files stay on your device
Batch processing
Priority support
Upgrade — starting at $6.99/mo
Upgrade to Full Version

Unlock the Full Power of MBOX Counter

Remove daily limits, process larger files up to 500 MB, enable batch processing, and get priority support.

Buy Full Version — $6.99/moor $300 enterprise

File Viewers includes:

  • 21 file viewers included
  • Unlimited daily uses
  • 100 MB file size limit
  • All file formats supported
  • Email analysis tools

Also available in the All Tools Bundle

FAQ

Frequently Asked Questions

Common questions about the MBOX Email Counter

Q1. How does the MBOX counter work?
MBOX files store multiple emails in one file. Each message is separated by a line that starts with the five characters 'From ' (word 'From' plus a space). The counter counts how many such lines exist in your file and displays that as the email count.
Q2. Do you upload my MBOX file?
No. Your file is processed entirely on your own device and never leaves it. Nothing is sent to our servers.
Q3. What is average email size?
It's the file size of the MBOX divided by the number of emails. So total size ÷ count. It gives you a rough idea of how large each message is on average.
Q4. Does it work with Gmail MBOX?
Yes. MBOX files from Google Takeout use the same 'From ' separator. Drop the file and you'll get an accurate count.
Q5. Is the counter free?
Yes. The tool is free to use with no sign-up and no limits.
Q6. What if the count seems wrong?
Some MBOX files have non-standard content (e.g. a leading 'From ' line or escaped 'From ' in body). The counter counts every line starting with 'From '; in rare cases that can over- or under-count. For standard exports it's accurate.
Q7. Can I count multiple files?
The tool processes one file at a time. For multiple MBOX files, run the tool once per file and add the counts if needed.
Q8. How fast is it?
Processing time is shown after counting. It depends on file size and your device; typically it's under a second for files up to a few MB.
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