Gmail signature size limits: what actually gets cut off

Gmail does not show a warning when your signature is too long. It just clips it — sometimes silently, sometimes with a “[Message clipped]” notice that hides the whole thing. Knowing the limits in advance saves the embarrassment of discovering this from a client.

The 10,000 character limit

Gmail’s signature editor accepts up to 10,000 characters of HTML. This sounds like a lot, but it is easy to blow past if you are using a generator that outputs unminified markup. Inline styles on every element add up fast. A well-built signature should come in well under 5,000 characters.

The image size problem

Logos and profile photos embedded as data URIs (inline base64) count toward the character limit and can bloat the signature dramatically. A 200×200 JPEG at full quality can encode to 40,000 characters on its own — four times Gmail’s limit. Compress profile photos to the smallest size that still looks sharp. Signify caps photos at 88px and encodes at 88% JPEG quality, which keeps them under 6,000 characters.

Width and mobile wrapping

Gmail renders signatures inside a container that is roughly 600px wide on desktop. On mobile it can drop to 320–375px. Signatures built with fixed pixel widths wider than that will overflow and scroll horizontally — or just look broken. Use table-based layouts with relative widths and test on a narrow viewport.

What actually gets clipped

• The entire email body is clipped when the total message exceeds roughly 102KB. A heavy signature — large images, lots of markup — eats into that budget.
• Recipients see a “[Message clipped] View entire message” link, and many do not click it. Your signature and any content below the fold disappears.
• This is especially common with long email chains where the original thread is quoted. Keep signatures concise so they do not compound the problem.

The safe zone

Name, role, company, one or two contact links, and an optional headshot. That is it. Everything beyond that increases size without increasing usefulness. The signatures that never get clipped are also the ones that always look right.