Gmail refuses to save your signature and tells you it is too long. You look at it — a name, a title, a logo and three links — and cannot see how that reaches ten thousand characters.
The answer is that Gmail counts the HTML, not the text. Here is what is eating your budget and how to get back under the limit.
Gmail allows roughly 10,000 characters in a signature. Crucially, that counts every character of underlying HTML: tags, attributes, inline styles, and any image data stored inline.
A signature that reads as forty words on screen can easily be several thousand characters of markup. A badly built one can be forty thousand.
This is almost always the reason. Some editors embed images directly into the HTML by encoding them as text. A modest 40 KB logo becomes about 55,000 characters of markup on its own — five times the entire allowance.
The fix is to host the image and reference it by URL. A hosted image costs you around sixty characters instead of fifty thousand:
<img src="https://example.com/logo.png" width="180" height="60" alt="Logo">
How to spot base64: open the signature HTML and search for data:image. If you find it, that is your problem.
Office applications generate enormous amounts of hidden markup — conditional comments, class definitions, namespace declarations and per-character font tags. Pasting a signature designed in Word into Gmail can multiply its size tenfold.
If you must design somewhere else, paste into a plain-text editor first to strip formatting, then rebuild the styling in the signature editor.
Visual editors love repeating the same declaration on every element. A signature where each of fifteen table cells carries the same twelve-property style attribute wastes thousands of characters saying the same thing over and over.
Set styles on the containing element and let them inherit where you can. Remove properties that match the default anyway.
Long UTM strings add up. Five links with a full set of campaign parameters can run to six hundred characters of pure query string.
Keep the parameters short, or use a redirect on your own domain that expands to the tracked URL.
A clean, well-built signature with a logo, a photo, four social icons and a banner should sit comfortably between two and four thousand characters.
There is a second threshold worth knowing. Gmail clips any message over about 102 KB and hides the rest behind a “view entire message” link — which is exactly where your signature lives. Heavy signatures on long reply threads are the usual cause. Our size guide covers the numbers to stay under.
The Mail Ink generator outputs compact markup with externally hosted images, so signatures fit inside Gmail’s limit without you having to audit anything by hand.