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    Free toolsAspect ratio checker

    Aspect ratio checker for social media

    Drop a picture, or type its width and height, and see whether Instagram, Threads, Telegram and the other networks that take pictures accept its shape. Where one refuses, the table gives the exact reason, the nearest ratio that passes and a size that fits, and you can crop to it right here. The picture stays in your browser.

    Or type the size in pixels
    Try a shape

    Too many bytes rather than the wrong shape? Use the image compressor.

    Per network

    Choose a picture or type its width and height to see every network's verdict.

    NetworkTakesVerdictNearest that passesCrop
    Instagram4:5 – 1.91:1——
    TikTokAny——
    FacebookAny——
    Threads1:10 – 10:1——
    LinkedInAny——
    PinterestAny——
    BlueskyAny——
    MastodonAny——
    Telegram1:20 – 20:1——
    DiscordAny——
    TumblrAny——

    The verdict comes from Preflight's validator once you type or choose a file.

    Aspect ratios by network

    Aspect ratios by network
    NetworkAccepted ratio (width:height)As numbersOther pixel rulesNotes
    Instagram4:5 – 1.91:10.8 – 1.91320–1440 px wideFeed pictures from 4:5 to 1.91:1. The API takes JPEG only and 8 MB; Preflight converts and scales anything else to 1,440 px wide.
    TikTokAny——Photo posts take JPEG; Preflight sends a copy no larger than 1080 × 1920 px. TikTok states no byte limit.
    FacebookAny——Any ratio. Facebook delivers photos at 2,048 px on the long side.
    Threads1:10 – 10:10.1 – 10320–1440 px wideUp to 10:1 either way, and 320 to 1,440 px wide; outside that Threads rescales the picture.
    LinkedInAny—under 36,152,320 pixels in totalAny ratio, but fewer than 36,152,320 pixels in total (width × height).
    PinterestAny——Takes any ratio; 2:3 is what the grid is drawn for.
    BlueskyAny——The record takes 2,000,000 bytes (decimal, not 2 MiB) per picture. Any ratio.
    MastodonAny——16 MB is the default; each server sets its own ceiling and scales pictures to about 8 megapixels.
    Telegram1:20 – 20:10.05 – 20width + height ≤ 10,000 pxPhotos up to 20:1 either way, with width plus height of 10,000 px at most.
    DiscordAny——10 MB a file and 25 MB a message in total. Any ratio.
    TumblrAny——Any ratio. Preflight sends a copy up to 2,048 px.

    Why a network refuses a picture for its shape

    Most networks take a picture of any shape and crop it themselves in the feed; a few refuse it before it is published. Instagram is the one people meet: a feed picture has to be between 4:5 and 1.91:1, so a tall 9:16 phone screenshot comes back with an error rather than a crop. Threads takes up to 10:1 in either direction and Telegram up to 20:1, with the further rule that the width and height together may not exceed 10,000 pixels. Everything else in the table above takes any ratio, and a refusal there is about size or format instead, which the image compressor handles.

    The ratio is simply width divided by height. 1080 × 1350 is 0.8, which is 4:5, Instagram's tallest allowed portrait. 1080 × 566 is about 1.91, its widest landscape. A square is 1. The checker works the number out from the picture's real pixels after applying the orientation a phone stores in the file, so a photo that is wide in the file but upright on your screen is measured the way a viewer sees it. The tolerance the validator allows (0.005 on Instagram) is built in, so a picture that is a pixel off an exact 4:5 is not turned away.

    How to fix a picture that is the wrong shape

    There are two honest fixes. Crop it, which loses the edges, or add bars, which keeps the whole picture but needs an editor; this tool only does the first, from the centre, to the nearest ratio the network takes. It rounds inward so the result is never a pixel outside the limit, shows you the area it keeps with a thirds grid, and saves a full-resolution JPEG you can download. If the subject is not in the middle, crop in your own editor and use the table to confirm the result.

    Nothing is uploaded: the picture is read and cut in your browser. The verdict is also sent, as a width and a height, to the validator Preflight runs before a scheduled post goes out, so the answer here is the one the composer would give. The same rules, with file sizes and formats, are in every network's limits, and the Instagram image size guide goes through the pixel dimensions.

    Questions

    Instagram

    What aspect ratio does Instagram accept for a feed picture?

    From 4:5 (portrait, 0.8) to 1.91:1 (landscape, 1.91). Preflight's validator allows a slack of 0.005 either side for rounding, so a 1080 × 1350 picture passes and a 1080 × 1920 one is refused with a request to crop it. Stories and reels are a different object and take 9:16.

    Networks

    Which other networks refuse a picture by its shape?

    Threads takes pictures up to 10:1 in either direction, and Telegram up to 20:1 with width plus height of 10,000 pixels at most. The others in the table — Facebook, LinkedIn, Pinterest, Bluesky, Mastodon, Discord, Tumblr and TikTok photos — take any ratio, though they may crop it in a feed preview.

    Privacy

    Is my picture uploaded to check or crop it?

    No. The browser reads the picture's width and height itself, and the crop is cut on a canvas on your device. The only request is the width and height (and the type and size, if you chose a file) sent to Preflight's validator so the verdict is the one a scheduled post would get; the picture itself is never sent.

    Cropping

    How does the crop decide what to keep?

    It keeps the largest centred area with the nearest ratio the network takes, cutting equally from both sides, and rounds inward so the result never lands a pixel outside the limit. If the subject is off-centre, crop it in your editor first and use this tool to confirm the shape. The crop is saved as a JPEG at full resolution, so run it through the image compressor if it is over the network's size limit.

    Write it once. Let the rules be our problem.

    Preflight checks every post against each network's rules before it leaves, then publishes it to twelve networks. Free plan, no card.

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