Gmail clipped my email: the 102 KB limit and how to stay under it

If Gmail shows "[Message clipped] View entire message" at the bottom of your email, the HTML was too big. The usual figure is about 102 KB of code, counted in bytes of markup, not in words. This page says what is reported, what is not known, how to measure your own file in seconds, and what actually makes transactional emails large (measured on 14 real ones, not guessed).

What is reported, and what is not documented

Email providers consistently report that Gmail clips a message above roughly 102 KB, shows the first part, and hides the rest behind a link. Sources: ContactMonkey, Zoho and ActiveCampaign. Two things to keep straight:

• Google does not publish the number. It is an observed behaviour. Treat 102 KB as a ceiling to stay well below, not a target, and expect it could change.
• It counts code, not visible text. A short email with heavy inline styles can be larger than a long plain one.

The reported cost of being clipped is real: the end of the message is hidden, which is where footers, unsubscribe links and any tracking pixel sit (Zoho and Maestra both say so). For a transactional email the footer often holds the support address, so a clipped receipt hides the way to ask about it.

Measure your own file in ten seconds

wc -c receipt.html

That prints bytes; divide by 1,024. Or paste the HTML into the free email HTML checker, which does the sum, flags an error at 102 KB and a warning from 80 KB, and lists the other things worth fixing at the same time. The same code is on GitHub as mailroom-check for the command line.

Measure the HTML your sending system actually sends, not the template you edit. Templating engines, tracking-link rewriting and a footer your provider injects all add bytes after you have finished. Send yourself the real message and view the source, or save it as .eml and check the HTML part.

What makes a transactional email big

Measured on the 14 emails of Mailroom Kit (HTML only, sample data, built from system fonts and no images): they range from 6.3 KB to 10.3 KB. Where the bytes go in the largest one, the receipt:

• Inline styles are 55% of the file. Email clients drop or rewrite <style> blocks, so every cell carries its own style="...". This is the main cost and why a long table grows fast.
• One more paragraph adds 298 bytes. At that rate, about 314 extra paragraphs would be needed to reach 102 KB. Ordinary copy is not the problem.
• One more row in a facts table adds 525 bytes (label and value, with borders). A 20-row order table costs about 10.3 KB; a 500-line statement would not fit in the same style, which is why long lists belong behind a link, not in the email.
• The hidden preheader filler adds 720 bytes (it stops inboxes pulling body text into the preview). Cheap, but it is bytes.

The big offenders in real emails are elsewhere, and none of them is in this kit: HTML pasted from a word processor or web page (hidden attributes and classes everywhere), images embedded as base64 (Gmail does not show those anyway), long tracking URLs repeated on every link, and whole conversations or test sends threaded into one large message (reported by Swift Digital).

Staying under it

1. Keep the email to one job. One heading, one paragraph or two, one action. Link to the rest.
2. Do not put long lists in the email. Show the total and link to the invoice or the export.
3. Write the HTML yourself or from a clean template, never by pasting from a document editor.
4. Use system fonts. No @font-face, no external stylesheet; both add bytes and load in few clients.
5. Keep URLs short (a token in a query string, not a path of IDs), and print each link once.
6. Check the real message your system sends, with your footer and tracking added.
7. Always send the plain-text part as well. It is small, and it is what a clipped or image-blocking reader can still use.

If you would rather start from emails that already pass, with the checks built in, Mailroom Kit is 14 finished transactional emails; each passes the checker with no errors or warnings and the largest is 10.3 KB. Open the live demo to see four of them.