Check Image Dimensions and File Size Online (Free Guide)
To check an image's dimensions and file size, drop it into a browser-based image size checker — it instantly reports the width, height, file size, aspect ratio and megapixels, and you can drop a whole batch to compare them in one table. Nothing is uploaded, so it works on confidential assets too.
Whether you are auditing a folder of exports before a deploy, confirming a social banner meets a platform spec, or checking whether a photo has enough resolution to print, knowing an image's exact measurements takes the guesswork out of the job. This guide walks through what each measurement means and how to read them fast.
Who needs an image size checker
Image dimensions decide how content displays; file size decides how fast it loads and whether an upload form will accept it. Developers use a checker to verify thumbnail and hero dimensions before shipping. Designers confirm their export sizes match the brief. Marketers make sure a graphic hits the 1200×630 Open Graph target or the 1080×1080 Instagram square. Anyone preparing images for print needs the megapixel count to know if a photo will hold up at the chosen size. A checker answers all of these in a single glance.
How to check image size in your browser
- Drag one or more images into the upload area, or click to browse and select a batch.
- Read each file's width, height, file size, aspect ratio and megapixels in the results table.
- Scan multiple rows together to spot outliers — an oversized asset, an odd aspect ratio, or a file that's too heavy for upload.
- Click Clear whenever you want to start fresh with a new set of images.
Image size vs. file size vs. aspect ratio
These three terms get mixed up constantly, yet they measure completely different things. Here's how they compare.
| Measurement | What it describes | Example |
|---|---|---|
| Image size (dimensions) | How many pixels wide and tall the picture is | 1920×1080 |
| File size | How much storage the file occupies on disk | 350 KB |
| Aspect ratio | The shape of the image, independent of resolution | 16:9 |
| Megapixels | Total pixels, used to judge print capacity | 2.1 MP |
Two images with the exact same 1920×1080 dimensions can have wildly different file sizes depending on format and compression — one might be a 4 MB PNG and the other a 200 KB JPEG. That's why checking both numbers together matters when you're optimising for the web.
Key features
- Checks multiple images at once in a clean comparison table.
- Reports width, height, file size, aspect ratio and megapixels for every file.
- Simplifies aspect ratios to familiar forms like 16:9 or 4:3.
- Supports JPG, PNG, WebP, GIF, AVIF, SVG and more.
- Instant results with no upload — 100% private.
- Free, no sign-up, and works offline as a PWA.
Try the Image Size Checker now — it's free and runs entirely in your browser.
Frequently asked questions
How do I check the size of an image?
Drop the image into the checker and it immediately displays the pixel dimensions, the file size in KB or MB, the aspect ratio and the megapixel count. Drop a whole batch to compare every file side by side in one table.
What is the difference between image size and file size?
Image size refers to pixel dimensions such as 1920×1080, which control how large the picture displays. File size is the storage the image occupies, like 350 KB, and depends on format and compression. Identical dimensions can produce very different file sizes.
How is aspect ratio calculated?
Aspect ratio is width divided by height, reduced to the smallest whole numbers — so 1920×1080 becomes 16:9. It describes the image's shape regardless of resolution, which matters when you're fitting pictures into fixed layout slots.
What image sizes do social platforms need?
Common targets are 1200×630 for Facebook and Open Graph previews, 1080×1080 or 1080×1350 for Instagram posts, 1600×900 for X, and 1280×720 for YouTube thumbnails. Use the checker to confirm your exports before uploading.
How many megapixels do I need to print?
At 300 DPI, a 6×4 inch print needs about 2.2 MP, an 8×10 needs roughly 7.2 MP, and an A4 page needs around 8.7 MP. The checker shows each image's megapixels so you can match them to your intended print size.
Related free tools
- Image Resizer — scale an image to the exact dimensions you need.
- Image Compressor — reduce file size before uploading.
- Image DPI Checker — read the print resolution stored in a file.
- Image Metadata Viewer — inspect the full EXIF details of any image.
Built by ByteVancer
ByteTools is a free product of ByteVancer, a software and web development studio that builds web apps, SaaS platforms and custom software for businesses. If you're planning a product or need engineering help, explore ByteVancer's services and reach out to start a project.
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