og:image file is too large

What you are seeing: Previews are slow to appear, or the image renders on some platforms but not in WhatsApp and other messaging apps.

The limits are not the same everywhere

Facebook accepts up to 8 MB, and LinkedIn and X up to 5 MB, which makes it easy to assume a heavy image is fine. WhatsApp is the constraint that actually bites: Meta's guidelines for WhatsApp link previews set the image limit at 600 KB, and above that the preview arrives with no picture.

WhatsApp also wants the image at least 300 pixels wide and no wider than 4:1, which a 1200 × 630 image already meets.

Because WhatsApp is often where links get shared one-to-one, a card that works everywhere except there is a card that fails at exactly the moment someone is recommending you personally.

Stay under 600 KB, ideally around 300 KB

Under 600 KB clears every platform's documented limit, WhatsApp's included, and this checker warns above it. Around 300 KB leaves headroom for slow connections. A well-compressed 1200 × 630 image lands comfortably under 200 KB in most cases, so this is usually achievable without any visible quality cost.

Crawler timeouts are the other reason to care. A slow fetch on a cold CDN edge can exceed the crawler's patience, and a timeout produces a card with no image at all rather than a card with a slow image.

How to get the size down

Choose the format by content. Photographs compress far better as JPEG at quality 80 to 85 than as PNG. Flat graphics with text and solid colours are the opposite — PNG-8 with a reduced palette will beat JPEG both on size and on how crisp the text looks.

Do not export at 2400 pixels wide expecting to serve retina. Social platforms scale the image themselves, and 1200 wide is already the size they design around.

WebP is well supported by the major crawlers now, but it is still the format most likely to be dropped by a smaller platform or an in-house link unfurler. If you need maximum compatibility, stay on JPEG or PNG.

Frequently asked

Why does my image work on Twitter but not WhatsApp?

Almost always file size. X accepts images up to 5 MB, but Meta's limit for WhatsApp link preview images is 600 KB. Compress the image to around 300 KB and it will show in both.

Can I use WebP or AVIF for og:image?

WebP generally works on the major platforms. AVIF support is still patchy. Since a social image is one small file served rarely, the compression win is not worth the compatibility risk — a well-optimised JPEG or PNG is the safer choice.