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Image compressor: get a picture under a network’s file limit

Bring a photo under the file limit X, LinkedIn, Bluesky or Instagram publish, or any size you set, losing as little as possible. Free; nothing is uploaded.

By Mellow · Updated October 12, 2026

Bring a picture under a file limit

Choose picturesUp to 20 at a time. They stay in this page: nothing is uploaded.

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How small does a picture have to be for each network?

It depends on the network, and the limits are far apart: Bluesky is the tightest at 1 MB, while Pinterest takes 20 MB. A photo straight from a phone or a camera is often several megabytes, which is over the smaller limits. The compressor brings a picture under the limit you choose by lowering JPG quality first and the number of pixels only when it has to.

File limits for a picture, network by network

Network	Limit	What its page says
Bluesky	1 MB	Bluesky’s documentation limits an image to 1,000,000 bytes on one page and 2 MB on another. Posts in depth (images)
YouTube thumbnail	2 MB	A custom thumbnail can be up to 2 MB from a phone and 50 MB from a computer. Add custom thumbnails on YouTube
LinkedIn Page	3 MB	A Page’s logo, cover and link images are PNG or JPEG up to 3 MB. Image specifications for your LinkedIn Pages and Career Pages
X	5 MB	Photos can be up to 5 MB. How to post photos or GIFs on X
LinkedIn	5 MB	A photo in a post can be up to 5 MB. Share photos on LinkedIn
Instagram	8 MB	Through Instagram’s API, which scheduling tools use, a JPEG can be up to 8 MB. Instagram Graph API, IG User media (image specifications)
Threads	8 MB	Through Threads’ API a picture can be up to 8 MB. Threads API overview, media specifications
TikTok	20 MB	Through TikTok’s API each photo can be up to 20 MB. Content Posting API, media transfer guide
Pinterest	20 MB	An image Pin can be up to 20 MB on the web. Review Pin specs

Every figure is from the network’s own page, read on 7 October 2026. The compressor aims a byte under each, so “up to” and “less than” are both met. Networks that publish no file limit for an ordinary post are not in the table.

How the compressor gets there

A file already under the limit is left alone. Compressing it again would only take quality away.
Quality first. The picture is saved at full size at falling JPG quality, and the first file that fits is kept.
Pixels only if needed. When no quality fits, the picture is made a step smaller and the qualities are tried again.
Very large pictures start smaller. One over 16 megapixels is made that size to begin with.

Questions

How do I make a picture small enough to upload?

Choose the picture and the limit it has to get under. The compressor saves it as a JPG at the highest quality that fits; only if no quality fits at full size does it make the picture smaller, a step at a time. It shows the size before and after, and the pixels it ended at.

What is the file size limit for a picture on each network?

Bluesky: 1 MB; YouTube thumbnail: 2 MB; LinkedIn Page: 3 MB; X: 5 MB; LinkedIn: 5 MB; Instagram: 8 MB; Threads: 8 MB; TikTok: 20 MB; Pinterest: 20 MB. Each is from the network’s own page, listed in the table on this page; some apply to posts made through the network’s API rather than its app.

Will the picture look worse?

A little, where it has to. JPG quality is lowered in steps from 92 and the first one that fits is used, so a picture that is only slightly over loses very little. A picture far over the limit is also made smaller in pixels. The page says which quality and which size it ended at, so you can judge.

What happens to a PNG, a WebP or a transparent picture?

One that is over the limit is saved as a JPG, which has no transparency: transparent areas become white. A file already under the limit is passed through untouched, whatever its type.

Are my pictures uploaded?

No. The pictures stay in this page and are compressed in your browser; the files are made on your own device.

Post the picture to every network at once

Mellow Hub takes the pictures from here into one post and sends it to the networks you connect, now or at a time you choose, with each network’s own caption where you want one. It checks each network’s rules for a post before anything is sent. Need the picture in each network’s size as well? Use the image resizer.

Post to Instagram and TikTok at once

Every social media image size, with sources

This tool is free and needs no account. Mellow Hub publishes your first 3 posts free, with no card; after that it is paid, with a 7-day free trial. It publishes only what you, or an assistant you have authorised, send or schedule.

Choosing a scheduler? Mellow Hub next to Buffer, Metricool and Postiz, from each one’s own pricing page, including where another is cheaper.

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