Keeping AI-generated banners on brand: logo, colors and fonts
AI makes the first banner quickly. The tenth one is where problems show up: the blue is a different shade, the logo is too small in one size and the button text uses different capitalization in every format. This guide covers how to put together a small brand kit and give it to the generator, and what to check before you upload the banners to Google Ads.
Key takeaways
- Put together a one-page brand kit: logo files, colors as HEX codes, one or two fonts, a few words on tone and the image style you want and don't want.
- Give the generator exact values. Words like "on brand" or "modern" don't tell it anything.
- Small banner text needs a contrast ratio of at least 4.5:1 against its background.
- Review the smallest size first. That's where the logo and text usually break.
Contents
Why AI-generated banners drift off brand
An image model doesn't know your brand. All it has is what you put in the prompt. If the prompt is vague, every generation interprets it differently:
| You write | What you get | Write instead |
|---|---|---|
| "Blue" | A different blue every time | #4F46E5 for the CTA, applied by the layout |
| "Modern style" | Neon one day, minimal beige the next | A fixed style sentence (see below) |
| "Add our logo" | A distorted, made-up logo | Your real logo file placed on top |
| "Our usual CTA" | "Learn More", "learn more", "LEARN MORE" | "Start free trial", in sentence case |
Leave the brand elements to the layout. The image model should only handle the scene.
Put together a one-page brand kit
| Item | What to prepare |
|---|---|
| Logo | SVG or transparent PNG. Prepare a horizontal version and a square symbol, each in a light and a dark variant. |
| Colors | HEX codes for the primary, secondary, accent and neutral colors, and a note on which one is used for the CTA. |
| Typography | One font for headlines and one for body text (it can be the same font), with the weights you use. |
| Image style | One fixed sentence you add to every prompt. |
| Don'ts | Imagery you never use, such as stock handshakes, neon gradients or people looking at the camera. |
| Voice | Three words that describe the tone, the CTA wording you've agreed on and the capitalization rule. |
Logo: size, clear space and versions
- Minimum size. Decide the smallest height at which your logo is still readable. For a wordmark on a 320×50 banner that's often around 20–24 px. If the full wordmark doesn't fit, use the square symbol.
- Clear space. Leave empty space around the logo, for example the height of one letter of the wordmark, so the logo doesn't touch the edge of the banner or the headline.
- Light and dark versions. Choose the version by what's behind the logo. A dark logo on a dark photo is the most common problem.
- Google's logo assets. Responsive display ads and Performance Max need a square 1:1 logo (1200×1200 recommended, 128×128 minimum) and accept a 4:1 landscape logo (1200×300 recommended). Make both from your source file. Don't stretch one into the other.
Color: consistent and readable
Choose one color for the CTA button and use it in every banner. People learn to recognize it as the button, and campaigns look consistent across placements.
Then check contrast. WCAG 2.x AA requires at least 4.5:1 for normal text and 3:1 for large text. Text on a banner is small, so treat almost all of it as normal text. Two blues that look similar can give very different results:
When text sits on a photo, the contrast changes across the image. A dark overlay or a solid panel behind the text keeps it readable whatever the photo looks like.
Typography that survives small sizes
- One font family, or two at most. Use weight to show what's important: bold for the headline, regular for the description, semibold for the CTA.
- One capitalization rule. "Start free trial" in one banner and "START FREE TRIAL" in another look like two different brands.
- Shorten the text instead of shrinking it. If the headline doesn't fit on 320×50, the fix is fewer words.
Imagery: one style sentence, every prompt
To keep AI imagery consistent, write one style sentence and paste it into every prompt without changing it. Describe the subject separately for each banner. The style stays the same:
Style: natural window light, warm neutral palette with soft
terracotta accents, shallow depth of field, minimal props,
calm uncluttered background, no text, letters or logos.Add the "don'ts" from your brand kit to the same block. For the rest of the prompt (offer, audience, layout), use our guide to writing banner prompts.
Consistency across sizes
Banners drift off brand most often when the set is resized. If each size is made separately, each one ends up with a slightly different image, crop and logo size. A better way is to start from one master scene and lay out the text, CTA and logo again for each shape, with the same rules.
AdflowKit works this way. It generates one master scene and crops each format from it, then places your uploaded logo and the real text on top. In the editor you can change the headline, colors, overlay or logo position and apply the change to the whole pack without generating a new image. That's useful when you want to test one change at a time.
Pre-upload checklist
- The logo is sharp, uses the right light or dark version and has clear space in every size.
- The CTA uses the brand color and the agreed wording in every size.
- All text has a contrast ratio of at least 4.5:1 against its background.
- The headline is readable on 320×50 and 320×100 at 100% zoom.
- Nothing important is cut off in the narrow formats (728×90, 160×600).
- Capitalization and punctuation are the same everywhere.
- File sizes are within Google's limits: 150 KB for uploaded images, 600 KB for HTML5 ZIPs (see sizes and limits).
- Square and landscape logo assets are ready for responsive display ads.
FAQ
Can AI keep my exact brand colors?
Image models only roughly match colors, even when you give HEX codes. Brand colors for the CTA, text and overlays should be applied by the layout, not drawn by the model. Use the prompt to keep the scene's colors close to your palette.
Should my logo be part of the AI-generated image?
No. Add your real logo file on top of the image. Generated logos get distorted, and you couldn't move or swap the logo later.
What's the minimum text contrast for banners?
Aim for at least 4.5:1, the WCAG AA level for normal text. Most banner text is small, so the 3:1 level for large text rarely applies.