What’s the ideal HTML-to-text ratio?

There's no magic number carved into an RFC somewhere, but the rough target most deliverability folks quote is 60% text to 40% HTML markup. That ratio isn't about how the email looks. It's about what spam filters see when they tear open the source.

Here's why filters care. Back in the early 2000s, spammers figured out they could dodge text-based filters by shipping emails as one big image with almost no real text. Filters couldn't read the picture, so they couldn't score it. Modern spam filters learned that lesson and now penalize emails where there's very little actual text to analyze. Alt text helps accessibility but doesn't count toward your ratio the way body copy does.

What actually counts as "text" in the ratio:

• Readable copy inside <p>, <li>, headings, and table cells. This is your real text weight.
• Link anchor text. Your CTA button label counts (it's text inside the HTML).
• Alt text on images. Helpful for accessibility, but filters weight it lower than body copy.

How to actually hit a healthy ratio without redesigning:

• Add a short intro paragraph above your hero image. Two or three sentences. Your filter score improves and so does the experience when images are blocked.
• Break long image blocks with a line of context text between them.
• Put your main offer or message in real text, not inside the image. If Gmail blocks the image by default (and it often does for first-time senders), the reader still gets the point.
• Check your final email by copying the plain-text preview. If it reads like a shopping list of link URLs, you're image-heavy.

Want to test what a filter actually sees? Run your email through our Review My Emails tools, or ping us on the SOS hotline if a specific campaign is getting flagged. Next up: image-to-text balance goes deeper on the image side.