Free Mastodon Image Resizer

What is a Mastodon image resizer?

A Mastodon image resizer cuts a photo to the exact pixel sizes Mastodon uses, so nothing gets cropped or blurred when you upload it.

This one has every Mastodon size in one place. It makes each file at a high quality and keeps it under Mastodon's upload limit.

Every Mastodon image size in 2026

Here are all four sizes:

The resizer has every size in this table. Pick the ones you need, and each becomes its own file.

Tips for Mastodon images

A few sizes come with rules worth knowing:

• Post image – Previews are 16:9; set a focal point in Mastodon so other shapes crop well.

The resizer draws the safe areas and round crops on each preview, so you see them before you download.

Mastodon upload rules

Here's what Mastodon accepts:

• Formats – WEBP, PNG, GIF, JPG.
• File limits – 2 MB, 16 MB, depending on where the image goes.

When a file comes out over a size's limit, the resizer makes it again at the best quality that fits, the same size.

Examples

This is my own photo of Stockholm at sunset, over Fotografiska, cut to four Mastodon sizes by this resizer:

I kept the sunset in every crop, the part of the photo that matters most.

Compared with Buffer

Buffer's free image resizer has a page for most networks. I ran the same photos through both on October 1, 2026:

On the same photos, cut to LinkedIn, Instagram, Pinterest and YouTube sizes, this resizer's JPGs scored within about a point of Buffer's and were 13% to 24% smaller.

The first crop matters too. On my Panama City photo, Buffer's LinkedIn cover started on the houses below the sunset, and this resizer's started on the sunset.

Buffer's Mastodon page lists 8 MB. Mastodon's own documentation says images can be up to 16 MB.

How I tested

I tested on October 1, 2026, with two of my own photos, Stockholm and Panama City at sunset, 1,536 × 2,048 each.

Above 80 means the same side by side at 100%. Both tools' files scored 85 to 88 where both cut the same area.

Where these sizes come from

Every size on this page is from Mastodon's own pages, checked on October 1, 2026:

• Mastodon documentation: Posting
• Mastodon documentation: Setting up your profile

When a page gives a range instead of one size, I picked the sharpest size inside it and said so in the tips.

Who is the Mastodon image resizer for?

It's for anyone posting on Mastodon:

• Mastodon character counter – people writing posts to the limit
• Post image generator – anyone turning a post into an image
• Remove background – people making a clean avatar
• Compress image – anyone making a photo smaller first

Social media managers use it to make every Mastodon size from one photo in a minute.

More free image resizers

Here's a resizer for each network, plus the one for any size:

• LinkedIn image resizer – every linkedin size, posts to page covers
• Instagram image resizer – posts up to 3:4, stories, reels and covers
• Facebook image resizer – posts, page and group covers, stories
• X image resizer – every post shape, header and profile photo
• Pinterest image resizer – pins, full-screen pins and profile covers
• YouTube image resizer – thumbnails, shorts covers and banners
• TikTok image resizer – full-screen, square and carousel images
• Threads image resizer – posts at the 1440 px threads keeps
• Bluesky image resizer – posts, banner and avatar under the limits
• Google Business Profile image resizer – photos, cover and logo for google
• Social media image resizer – every size of 11 networks at once
• Image resizer – any size, or a percent

They all work in your browser, with every size from the network's own pages.