Google Ads Preview —
Pixel-Accurate Responsive Search Ad Simulator

Responsive Search Ads (RSA) have firm character caps: each headline is limited to 30 characters and each description to 90 characters. Google mixes and matches your headlines and descriptions automatically, showing up to three headlines and two descriptions at once. The counters in the simulator above enforce these caps as you type, so a clamped field is impossible to miss.

The 30-character cap is only half the story. Google renders headlines in a row separated by vertical bars, and the desktop ad slot is roughly a 600px-wide container. Three headlines that each pass the 30-character check can still overflow that width — in which case Google drops the trailing headline rather than wrapping it. This tool measures each headline by its true rendered pixel width using an HTML5 canvas, exactly the way a browser paints Arial, instead of guessing with an average-character estimate. That means the preview drops Headline 3 at the same point Google would.

Front-load the headlines that must always appear, and pin them to positions 1 and 2 in Google Ads if they are non-negotiable. Keep wide characters (capital letters, "W" and "M") in mind — a 28-character all-caps headline can be physically wider than a 30-character lowercase one. The live pixel meter shows the difference instantly.

Every measurement happens in your browser; nothing is uploaded. Draft your RSA assets here, confirm that your most important headlines clear the pixel container on desktop, and paste the finished copy into Google Ads with confidence that nothing important silently disappears.