Image dimensions checker — read pixel size, aspect ratio and DPI from any photo

Platform dimension specifications at a glance

Every social platform and publishing context has a preferred image size. Submit something too small and the platform upscales it, introducing visible blur. Submit something with the wrong aspect ratio and the crop removes content you intended to show. The table below lists the dimensions that matter most in practice.

What DPI means — and what it does not mean

DPI (dots per inch) is a print-output parameter, not a screen-quality parameter. It describes how densely the pixels will be arranged on paper at a given physical size. A 3000 × 2000 px image at 72 DPI and the same image at 300 DPI contain exactly the same number of pixels — only the print instructions differ. Changing DPI in a metadata editor without resampling does not add or remove any pixel information.

Where DPI matters: sending files to a print shop. The standard is 300 DPI for sharp results at the intended print size. A 3000 × 2000 px image at 300 DPI prints at 10 × 6.67 inches. The same file at 72 DPI prints at 41.7 × 27.8 inches — blurry at that scale. The checker reads the DPI value from the EXIF block so you can confirm it matches your print spec without opening a dedicated image editor.

How aspect ratio is calculated and why it matters for cropping

Aspect ratio is width divided by height, expressed as the simplest whole-number pair. A 1920 × 1080 px image has a ratio of 16:9 because both numbers share the factor 120 (1920 ÷ 120 = 16, 1080 ÷ 120 = 9). The checker computes this automatically from the pixel dimensions.

Why it matters: when you upload an image to a platform that expects a specific ratio, the platform either crops from the centre, letterboxes with bars, or stretches to fill — none of which match what you designed. Instagram's feed enforces a 4:5 maximum height; a 9:16 portrait shot gets cropped to 4:5 and the top and bottom are cut. Checking the ratio before upload takes seconds and avoids that surprise.

Six real scenarios where checking dimensions first saves time

Preparing a product photo for an e-commerce listing: the store template requires images wider than 1000 px and enforces a 1:1 square crop. Running the checker on your draft confirms 1200 × 1200 px before you edit and export a batch of twenty.

Submitting a press release to a wire service: the image spec calls for exactly 1200 × 627 px and a minimum of 72 DPI. The checker confirms both numbers from the EXIF header. The submission passes automated validation on the first try instead of bouncing back with a vague size error.

A freelance designer handing off assets to a developer: the brief specifies hero images at 1920 × 1080 px. Checking each export before sending confirms none of the files were saved at half resolution by accident.

Uploading a YouTube thumbnail: the platform accepts anything down to 640 × 360 px but renders at 1280 × 720 px in most contexts. Submitting a 480 × 270 px draft means visible pixelation on desktop viewers. The checker flags the shortfall immediately.

Printing a banner for an event: the print shop requires 300 DPI at the finished print size. Reading the EXIF DPI value before sending confirms whether the file was exported from the design tool at the correct setting or left at the screen default of 72 DPI.

Auditing a batch of user-uploaded photos: a community platform reports that some profile pictures appear blurry. Checking dimensions on a sample reveals a subset uploaded at 200 × 200 px, far below the 400 × 400 px minimum the template expects. That narrows the fix to the upload-size validation on the client.

Four misconceptions about image dimensions

Misconception: a higher DPI setting makes a digital image sharper on screen. Screen sharpness depends entirely on pixel count. A 1200 × 900 px image at 300 DPI and the same image at 72 DPI look identical on any monitor because both files contain the same 1,080,000 pixels. DPI is only meaningful when the image is printed or when a print-oriented layout application uses it to calculate physical dimensions.

Misconception: resizing an image to the platform's recommended dimensions always produces the best result. If the source image is smaller than the target size, resizing up resamples the pixels and introduces blur. The right workflow is to start from a file larger than or equal to the target and resize down, not up.

Misconception: changing aspect ratio is the same as cropping. Stretching a 4:3 image to fill a 16:9 frame without cropping distorts it — every face and object in the frame becomes wider than the original. Correct aspect ratio adjustment is always a crop (which removes content) or a canvas extension (which adds blank space), never a stretch.

Misconception: file size and image dimensions are the same thing. A 1920 × 1080 px JPEG can range from 200 KB to 4 MB depending on compression level. File size reflects JPEG quality settings and content complexity, not just pixel count. A photographic scene compresses less efficiently than a flat-colour graphic at the same pixel dimensions.

Platform dimension claims worth verifying at source

Social platforms update their image specifications more often than most guides acknowledge. Instagram has adjusted its feed image ratios more than once since the format launched; Facebook has changed its Open Graph image minimum width requirements; LinkedIn has updated cover photo dimensions across personal and company pages at different points in time. The numbers in this page's table reflect current confirmed specifications, but if you're working on a campaign with real budget behind it, check the platform's own help centre before locking production dimensions.

A few things to look for when reading official platform documentation: the distinction between "supported" and "recommended" sizes (supported means the platform won't reject it; recommended means it renders well in the standard display context), the difference between the feed display size and the lightbox or expanded view size, and whether the spec shown applies to the uploaded file or to how it appears after the platform recompresses it. Most major platforms apply their own JPEG compression on upload regardless of the quality setting in your file, which can reduce visible quality even when the pixel dimensions are correct.

Screen pixel density (PPI) and what it means for your images

DPI is a print concept. The equivalent for screens is PPI — pixels per inch — and it describes the physical display's density, not the image file. A typical desktop monitor runs at around 96 to 110 PPI. A modern smartphone display typically runs at 400 PPI or higher. This matters for images because the same pixel count looks noticeably different depending on how large the display device renders those pixels.

Consider a 1080 × 1080 px image displayed at natural size on a low-density screen: it covers a reasonably large area and each pixel maps one-to-one to a screen dot. On a high-density phone screen, those same 1080 pixels occupy a much smaller physical area — sharper, but smaller. When an app or browser scales the image up to fill a larger region on a high-density display, it needs more source pixels than the minimum spec to avoid visible resampling.

This is why several platform recommendations publish a "2× retina" target alongside the standard minimum. Providing twice the pixel count where the platform needs it allows the platform to serve a higher-resolution version to high-density screens without upscaling. The image dimensions checker shows you the pixel count you have; whether that count is sufficient depends on the screen density of the audience you're designing for, not just the platform's minimum acceptance threshold.

A five-point checklist before you export or upload

Running through a short checklist before sending a file prevents the most common size-related rejections and display problems.

Pixel dimensions match the target spec. Look at the platform's recommended size, not just the minimum. Files at the minimum get accepted but often render at a lower visual quality than the recommended dimensions allow because the platform has less pixel data to work with when composing the display.

Aspect ratio matches the display frame. A file that passes the pixel count check can still fail a crop if the ratio is wrong. An image that is 1600 × 800 px — a 2:1 ratio — submitted to a context that crops to 16:9 will lose content on the sides or top. Verify the ratio column in the table above before committing to an export.

DPI matches the output destination. Screen destinations treat DPI as metadata only, so 72 is acceptable. Print destinations use it to calculate physical output size, so confirm 300 before sending to a press or print shop. This checker reads the DPI from the EXIF header so you can confirm it without opening a separate image editor.

File size is within the platform's upload limit. This checker shows file size alongside pixel dimensions. Most platforms document a maximum file size in their help pages; JPEG quality settings and image complexity both affect how large a file ends up at a given pixel count, so a high-quality JPEG of a photographic scene can be several times larger than a flat-colour graphic at the same dimensions.

The format is accepted at the destination. The checker reads JPEG and PNG files, which cover the majority of publishing contexts. If you're working with WebP, HEIC, or AVIF, confirm the target platform supports the format before building your export workflow around it. Format rejections tend to surface as confusing errors that take longer to diagnose than a quick format check would have taken.

Privacy: how the checker works without uploading anything

The tool uses the browser's File API to read the image into a local buffer. Pixel dimensions are read from the decoded image element, file size from the File object, and DPI from the EXIF header — all without network access. You can confirm this by opening the browser network panel (F12 → Network) while using the tool: there are no outbound requests.

That matters when the photo is a client deliverable, a document scan, or any file whose content you would not normally send to a third-party service. Local processing means nothing is stored, logged, or transmitted. If you also want to inspect or remove the full EXIF block from the same file, the metadata viewer runs the same way and shows every tag the file carries.

How this tool relates to other tools on this site

This checker focuses on the dimensional properties — width, height, aspect ratio, DPI — that determine whether an image fits a publishing context. For a complete picture of what the file stores beyond dimensions, the photo metadata viewer reads the full EXIF block: camera model, lens, capture time, GPS coordinates, and software tags.

If the metadata viewer reveals fields you want to remove before sharing, the metadata remover strips all EXIF, GPS, IPTC, and XMP in the same browser-only workflow. For removing only GPS coordinates while keeping camera data intact, the GPS remover targets just the location cluster.