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About this tool
Work out amp-img dimensions, retina source sizes and estimated file weight against the 200 KB AMP for Email limit.
AMP Email Image Size Guide turns a placement in your email column into the three numbers you actually need: the CSS display size, the source pixel size to export for retina screens, and an estimated file weight per format. It also builds the matching amp-img tag — AMP for Email forbids plain img and requires width, height and a layout attribute — and tracks the 200 KB ceiling Gmail places on the AMP part of a message. Weight figures are planning estimates from typical bytes-per-pixel rates, not encoder output.
Open AMP Email Image Size Guide on AltFTool — it loads instantly in your browser.
Pick a Placement — Full-width hero, Two-column card, Three-across product, Article thumbnail, Header logo or Inline icon — with an amp-img layout of responsive, fixed or intrinsic, then set Email content width (px), Pixel density to export for and the Aspect ratio width and height.
Choose an Export format (AVIF, WebP, JPEG 75/85, PNG-24 or GIF) and what the image contains, then enter how many images of this size the email has plus your AMP markup size (KB) and Inline amp-custom CSS (KB).
Read "Export the source at" for the pixel dimensions, check the AMP part used bar against the 200 KB limit, press Copy tag under Ready-to-paste markup, and compare weights in "Same image, every format".
Emits width, height and layout in the form AMP validates, including responsive's aspect-ratio behaviour.
Tracks the 200 KB AMP part limit and the 75 KB amp-custom CSS cap as you change inputs.
Shows the same image at AVIF, WebP, JPEG, PNG and GIF, with base64 overhead alongside.
The AMP HTML part must be under 200 KB in Gmail; larger messages fall back to the plain HTML part. Inline styles in <style amp-custom> are separately capped at 75 KB. Images referenced by HTTPS URL do not count towards the 200 KB, but base64 data URIs do.
Design to a 600 px content column and export at twice the display width for retina screens — so a full-width hero is 1200 px wide. Going past 2x roughly doubles the pixel count again for a difference few readers can see on a phone.
No. AMP for Email replaces <img> with <amp-img>, which requires an explicit width, height and layout attribute. Use layout="responsive" for images that fill the column, "fixed" for exact pixel boxes and "intrinsic" for logos that must not be enlarged.
JPEG remains the safe default because decoder support across mail clients is uneven. WebP is roughly 30% smaller at similar quality and AVIF smaller still, so serve them through a content-negotiating CDN and keep a JPEG for the fallback HTML part.