TL;DR: Wrong pixel dimensions stop your ads from serving. Fix them by matching Google's exact size requirements per campaign type, then reuploading. Use Smart Resize in Coinis Revise to scale any image to the right format in one click.
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Why Ad Dimensions Matter in Google Ads
Wrong dimensions are one of the top reasons image ads stop serving. Google Ads validates every upload automatically. A mismatched image gets rejected before it ever reaches a placement.
Common dimension errors and their impact on serving
The most common mistake is uploading an image that doesn't exactly match the required slot dimensions. Google Ads does not accept double-sized or high-DPI scaled images. A 640x100 image for a 320x50 slot will fail even if the aspect ratio looks right. Dimension mismatches prevent ads from serving entirely.
How Google Ads validates image specs
Per the Google Ads Help Center, non-compliant images are flagged automatically on upload. Your ad will show a "Not serving" or rejection status in the Assets section. You must remove or reupload the image with correct dimensions before the ad goes live.
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Standard Google Ads Dimension Requirements by Campaign Type
Get these specs locked in before you upload anything.
Performance Max image aspect ratios
Per Google's documentation on Performance Max image assets, campaigns require three aspect ratios. Landscape images must be 1.91:1. Square images must be 1:1. Portrait images must be 4:5 or 9:16. Covering all three formats improves your coverage across placements.
Display network ad sizes
The Google Display Network accepts standard banner sizes. The most-used formats are 300x250 (medium rectangle), 728x90 (leaderboard), and 120x600 (wide skyscraper). Pixel dimensions must match exactly. Per the Google Ads Editor Help documentation, Google Ads Editor rejects double-resolution images for these slots, even when the aspect ratio is correct.
File format and size limits
All image uploads must be JPG or PNG. Per Google Ads specs documentation, Performance Max images can be up to 5MB. Display ad banners are capped at 150KB. Both limits are hard stops. Exceed them and your upload fails immediately.
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How to Check Your Current Ad Dimensions
Catching problems early prevents wasted spend. Google surfaces this information directly in the interface.
Find ad specs in Google Ads interface
Open your campaign in Google Ads. Navigate to the Assets section. Click any image asset to view its current dimensions and serving status. Google flags non-compliant assets with a warning or "Not serving" label.
Identify dimension mismatches early
Download the flagged asset and open it in any image viewer. Check the pixel dimensions. Compare them against the required sizes for your campaign type. If they don't match exactly, the image needs to be corrected before it can serve.
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Step-by-Step: Correct Undersized or Oversized Ads
Follow these steps to fix a non-compliant image and get it back into rotation.
Reupload with correct pixel dimensions
Start from the highest-resolution source file you have. Open it in an image editor. Resize to the exact pixel dimensions required for your ad format. Do not scale up from a small source if you can avoid it. Export as JPG or PNG, staying within the file size limit. Upload the corrected file in the Assets section of your campaign.
Remove or replace non-compliant images
In the Assets section, find the flagged image. Click Remove or Replace. Google Ads stops serving the non-compliant creative immediately. Add your corrected image in its place.
Verify after changes
After uploading, check the asset status in Google Ads. Allow a few minutes for Google's automated validation to run. An "Eligible" status means the image passed. If errors persist, double-check the pixel dimensions against the official spec for your campaign type and re-export.
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Fix Common Dimension Issues Fast with Smart Resize
Manual resizing is slow. Smart Resize removes most of the work.
How Smart Resize eliminates manual dimension work
Coinis Revise includes Smart Resize. It takes any image and scales it to a target format automatically. No manual canvas math. No guessing at pixel values. Pick the format and it handles the rest. Note: Coinis does not publish directly to Google Ads today, but Smart Resize prepares your creatives for any ad platform you run.
One-click scaling to any Google Ads format
Upload your image to Coinis Revise. Select the target format. Smart Resize outputs a correctly sized asset, ready to drop into Google Ads. No Photoshop. No cropping by hand.
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Or skip the steps.
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Frequently Asked Questions
What happens if my Google ad dimensions are wrong?
Google Ads flags the image and stops it from serving. You'll see a 'Not serving' or rejection status in the Assets section of your campaign. Correct the pixel dimensions and reupload to fix it.
Does Google Ads automatically fix dimension issues?
Google Ads can auto-upscale some images with its built-in AI enhancement, but this is not reliable and should not be your primary fix. Always upload images at the exact required pixel dimensions for your campaign type.
What file formats and sizes does Google Ads accept for image ads?
Google Ads accepts JPG and PNG files. Performance Max images can be up to 5MB. Display banner ads are capped at 150KB. Images that exceed these limits will fail on upload.