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Free email QA tool · No signup

HTML email size checker

Measure the code behind your email before you send. Paste your compiled HTML to see its UTF-8 byte size and how much room remains in a conservative 100 kB planning budget.

Measured in your browser. This tool does not upload, save, or render your code. Use HTML exported by your email platform or MJML editor.

0 bytes (0.00 kB)

Paste HTML to check its size.

Budget: 100,000 bytes. A size check cannot guarantee that Gmail will show the entire message.

Why email HTML size matters

Long messages can hide important content behind a “View entire message” link. Mailchimp documents Gmail clipping messages larger than about 102 KB. This checker uses a lower, 100,000-byte planning budget to help leave room for changes after export.

The result measures the exact text you paste, including markup, styles, comments, and URLs. It does not download linked images or include their file sizes. An image embedded as a data URL does count because that data is part of the pasted code.

Read Mailchimp’s guidance on Gmail clipping. Your email platform may rewrite links or insert tracking code, so send a test from that platform and inspect the delivered message.

How to check an MJML email

  1. Compile your MJML and export the resulting HTML.
  2. Paste the HTML above. MJML source is smaller than its compiled table markup, so measuring source alone can mislead you.
  3. Remove unused sections and repeated formatting, then compile and measure again.
  4. Send a test through your email provider and check the complete message, including its footer and unsubscribe link.

Do not strip conditional comments or email-client fixes blindly. A smaller file still needs visual testing at desktop and mobile widths.

Does a small result guarantee no clipping?

No. The tool measures pasted UTF-8 HTML, not the final MIME message or Gmail’s processing. Sender additions, encoding, and threaded test messages can change the outcome. Treat the number as a pre-send check.

Is this an MJML validator?

No. Size and valid structure are different checks. Use the MJML validation workflow to review structure, and the email QA checklist before sending.

Need cleaner email code?

Generate a fresh template or repair an existing one, review the compiled output, and bring the exported HTML back here to measure it.

Open the MJML editorRepair an email