Image Resolution Checker

What does an image resolution checker show?

An image resolution checker reads the file you open and reports the specs that matter for print, web, and social: pixel width and height, aspect ratio, megapixels, file size, and DPI or PPI when the file embeds density tags. This free photo resolution checker runs in your browser on your device. The image is not uploaded to a Compresso server.

People also search for an image quality checker. Pixel size and file size help you decide if a photo is large enough for print or web. They are not a sharpness or AI quality score. If the megapixels are too low for your target size, start from a larger original before you compress.

People search for “image resolution checker,” “photo resolution checker,” and “how to check picture resolution” for the same reason: they need numbers before they commit. Guessing from a zoomed-in preview is how soft prints and rejected marketplace listings happen.

Pixels vs DPI (and why both matter)

Pixels are the grid that makes up the image. A 4000 × 3000 photo has 12 megapixels. That number does not change when you email the file.

DPI / PPI is density for print: how many of those pixels fit in one inch on paper. The same 4000 × 3000 file is about 13.3 inches wide at 300 DPI, or about 40 inches wide at 100 DPI. The pixels did not multiply. You only changed how large you ask the printer to spread them.

On screens, pixel dimensions and aspect ratio usually matter more than DPI tags. Many digital files have missing or default density metadata. When this tool shows DPI as unavailable, trust the pixel size for web work and ask your print lab for their preferred export settings for paper.

Common resolution targets people actually need

Exact platform rules change. Use these as planning ranges, then confirm with the destination:

• Print photos: often aim near 300 DPI at final size. A 6 × 4 inch print at 300 DPI needs about 1800 × 1200 pixels.
• Passports and ID photos: countries publish fixed pixel or millimeter sizes. Check the official checklist for your country before you crop.
• Social posts and stories: platforms publish preferred widths and aspect ratios (for example square 1:1 or portrait 4:5). Pixel height and width matter more than DPI.
• App Store and Play screenshots: each device class has required pixel sizes. A resolution check catches a wrong export before review.
• Web heroes and product shots: match the largest size your layout displays (and 2× for retina if you serve high-density assets).

If you only need a quick format shrink after dimensions look right, free browser tools like Compress JPG and Compress PNG run locally too.

When should you check resolution before compress or upload?

Check first when the destination has a hard size rule: print labs, government forms, marketplace product images, and store listing screenshots. Compression cannot repair a photo that is already smaller than the required width.

Check after export from a phone, Figma, Lightroom, or a client handoff. Filenames lie. “Final_web.jpg” is not a guarantee of 2400 px on the long edge.

Check before you burn time compressing a whole folder. One undersized hero in a batch of 200 files is cheaper to catch now than after upload day.

A practical loop: verify dimensions here → compress or convert one sample → spot-check quality → only then run a bulk job. For folder-scale work, see the bulk image compressor guide and batch processing basics.

How to check image resolution in this tool

1. Drop a JPG, PNG, WebP, GIF, or SVG onto the checker above (or pick a file).
2. Read width × height, aspect ratio, megapixels, and file size.
3. Note DPI when it is embedded; treat missing DPI as normal for many web exports.
4. Compare the numbers to your print size, platform chart, or CMS requirement.
5. If the file is large enough, compress or convert next. If it is not, go back to source.

Everything stays on your Mac or PC while the page is open. Close the tab when you are done if the photo is sensitive.

From one file check to bulk offline work

This page is for inspection, not mass encoding. When dimensions look right and you need to shrink many images (or videos) without uploading them, use Compresso on desktop: drag a folder, pick a quality preset, and write smaller copies on disk. Free and Pro limits are listed on the site; Pro is a one-time purchase for larger batches.

For Mac-focused offline context, see best offline image compressor for Mac. For a wider free-tool landscape, see best free image compressors.