What is image resolution, exactly?

On screen, resolution is the pixel dimensions of the image, its width times its height, like 1920 × 1080. That pixel count is the real measure of how much detail a file holds. DPI is a separate print tag; it does not change how many pixels you have. This checker reads the true decoded dimensions straight from the file.

How do I check the resolution of an image?

Drop the file above. It is decoded in your browser and the exact width and height in pixels appear instantly, along with the megapixel count and aspect ratio. Nothing is uploaded, so you can check private or work images safely.

What resolution do I need?

For the web, match the display slot: a full-width hero is often 1600 to 2000 px wide, a thumbnail 300 to 600 px. For print, multiply the print size in inches by 300: a 4 × 6 inch photo needs about 1200 × 1800 px. More pixels than the slot is wasted weight; fewer looks soft.

Is a higher resolution always better?

No. Beyond what the screen or print needs, extra pixels only make the file larger and slower with no visible gain. The goal is enough resolution for the use, not the maximum. If a file is far bigger than its display size, resize it down to cut the weight.

Does the DPI number affect on-screen resolution?

Not at all. Screens render by pixel and ignore the DPI tag, so a 1000 px image is 1000 px wide whether it is tagged 72 or 300 DPI. DPI only decides physical size on paper. This tool shows both so you can see they are independent.

Are my images uploaded to check them?

No. The file is read and decoded entirely in your browser to measure its resolution. Nothing is sent to a server, which you can confirm in your browser's Network panel.

Image Resolution Checker

Check image resolution online, free

Drop an image and see its true resolution: the exact width and height in pixels, the megapixel count, the aspect ratio, and any print DPI tag. It is read in your browser, so nothing is uploaded, and it works on JPG, PNG, WebP, AVIF and more.

Drop an image here, or click to choose

JPG, PNG, WebP, GIF, AVIF, BMP, TIFF, HEIC. Read entirely in your browser.

Files never leave your device
Runs in your browser
Free, no signup

How it works

1
Drop an image
Add a single file or several. Each is decoded in your browser to read its real pixel dimensions, with no upload and no wait.
2
Read the resolution
See width × height in pixels, total megapixels, the aspect ratio, and whether the file carries a print DPI tag.
3
Decide your next step
Compare it to what your screen, print or form needs. If it is oversized, resize down; if a form wants a DPI, set the tag.

What this checker tells you

The true decoded resolution

The image is decoded, not guessed from the file name or a header alone, so the pixel dimensions are exactly what software and browsers will see.

Pixels and DPI, side by side

Resolution and the print DPI tag are shown together, so it is clear that screen detail comes from pixels and DPI only matters on paper.

Private by design

Everything happens in your browser tab. The image is never uploaded, which you can verify in the Network panel, so it stays safe for work and personal files.

Where this helps

Is this big enough to print?

Before ordering a print, check the pixels against inches × 300. The checker shows the print size at 72, 150 and 300 DPI so you can see how large the file prints sharply.

Web

Right-sizing images for the web

A 6000 px photo dropped into a 1200 px column is wasted weight. Read the resolution, then resize down to match the slot and speed up the page.

Forms

Meeting an upload spec

Application portals often state a minimum or maximum pixel size. Check the resolution first to know whether you need to resize before uploading.

Workflow

Sorting a batch of photos

Drop several at once to compare their resolutions side by side and spot the low-resolution outliers that will not hold up when enlarged.

Tips that help

1
Width and height beat megapixels
Megapixels are a useful total, but layouts and print specs ask for width and height. Read those two numbers first; the MP figure is secondary.
2
More resolution is not free
Past the size your screen or print needs, extra pixels only add file weight and slow loading. Aim for enough, not maximum.
3
Ignore DPI for screens
On-screen sharpness depends on pixels and the display's density, not the DPI tag. Only worry about DPI when you are printing.
4
Can't enlarge missing detail
If an image is below the resolution a print needs, scaling it up cannot invent detail. Start from the highest-resolution original you have.

Image resolution: pixels, megapixels, and how much is enough

Resolution is the single most useful fact about an image, and also the most muddled. People mix it up with DPI, with file size, and with quality. This guide untangles it: what resolution actually measures, how megapixels relate to width and height, and how to judge whether a given image has enough resolution for the web post, the print, or the upload form in front of you. This checker reads the true pixel dimensions in your browser, with no upload.

Resolution is a pixel count, nothing more

An image is a grid of pixels. Its resolution is simply how many across by how many down, like 1920 × 1080 or 4032 × 3024. That number is the honest measure of how much detail the file can show, because every bit of detail has to live in some pixel.

Multiply the two and you get the total, usually quoted in megapixels: 4032 × 3024 is about 12 MP. Megapixels are handy shorthand for a camera or a print ceiling, but the width and height matter more day to day, because layouts and forms ask for those directly.

Crucially, resolution is not file size and not quality. Two 1920 × 1080 images can weigh wildly different amounts depending on compression, and a low-resolution image can still be perfectly sharp at a small size. Resolution just tells you how far you can scale before pixels start to show.

How much resolution is 'enough'?

Enough is defined by where the image will appear. On screen, match the slot it fills: a 1200 px wide content column needs roughly 1200 to 2400 px (the upper end for sharp display on high-density screens), not 6000. Anything beyond the slot is downscaled by the browser and only slows the page.

For print, the rule is pixels equal inches times the print DPI. At the 300 DPI most labs expect, a 4 × 6 print wants about 1200 × 1800 px, an 8 × 10 about 2400 × 3000. If your file has fewer pixels than that, no setting will rescue the sharpness, because the detail simply is not there.

So the workflow is: read the resolution, compare it to the target, and act. Too few pixels for a print is a hard limit. Too many for the web is easy to fix by resizing down, which also shrinks the file.

Resolution versus DPI, settled

DPI (dots per inch) is a print instruction stored as a tag. It says how tightly to pack the existing pixels onto paper. It does not add or remove a single pixel, so it changes print size, not resolution.

That is why 'save it at 72 DPI for web' is meaningless, because screens ignore the tag entirely and display by pixel. What governs web sharpness is the pixel resolution and the screen's own density, never the DPI number baked into the file.

This checker shows the pixel resolution and any DPI tag side by side precisely so the difference is obvious. If you need to set a print DPI without changing the pixels, that is the job of the DPI tool.

Frequently asked questions

Honest answers to what people ask before using this tool.

Check image resolution online, free

How it works

Drop an image

Read the resolution

Decide your next step