📐 How to Size CTA Text for Any Banner
One of the most common mistakes in banner design is guessing the CTA text size. It rarely matters on a large 300x250 banner, but on a narrow 728x90 leaderboard or a 320x50 mobile banner, oversized text can overflow the button or undersized text can vanish into the background.
This tool bases its calculation on whichever dimension is smaller — width or height — and returns a recommended text size, button height, and horizontal padding. Narrow banners are capped down to 12px, while banners with 250px or more of room can scale up to 36px to grab attention. The result is applied live to a preview button so you can see exactly how it looks.
Treat the output as a starting point — before shipping, check that the button doesn't get clipped inside the banner and that your copy doesn't wrap to a second line. If the copy is long, shortening the text is usually a better fix than shrinking the font further.
Frequently Asked Questions
Text that's too small hurts readability, so keep it at least 12px. For smaller banners, shorten your copy and emphasize only the key word instead of shrinking the font further.
Yes. Even with the right text size, low contrast against the background makes a CTA easy to miss. Use a button color that's clearly lighter or darker than the background.
Base your calculation on the smallest breakpoint's dimensions, then use CSS clamp() so the text scales up gracefully as the banner grows.