Image Dimensions Checker

What this tool shows you

Drop any image and instantly see: pixel dimensions (width × height), file size in KB or MB, the simplified aspect ratio (e.g. 16:9 or 4:3), megapixel count, and whether the resolution is suitable for print or web use. Check multiple images at once by dropping them all together.

Frequently asked questions

How do I find the dimensions of an image without opening it?

Drop it here — the dimensions appear in under a second. On Windows you can also right-click the file → Properties → Details tab. On Mac, right-click → Get Info → More Info. This tool works on any device including phones where file properties aren't easy to access.

What is a good image size for websites?

For full-width hero images: 1920×1080px at under 300 KB. For blog post images: 1200×630px at under 150 KB. For thumbnails: 400×300px at under 50 KB. If your image is larger than these targets, use the image resizer to reduce dimensions and the image compressor to reduce file size.

What resolution do I need for print?

Print requires 300 DPI (dots per inch). For an 8×10 inch print at 300 DPI, you need at least 2400×3000 pixels. For a 4×6 photo, 1200×1800 pixels. The tool shows a print-readiness note based on your image's pixel dimensions.

What is aspect ratio and why does it matter?

Aspect ratio is the proportional relationship between width and height. Common ratios: 16:9 (widescreen video, YouTube), 4:3 (classic TV, many cameras), 1:1 (square, Instagram), 4:5 (Instagram portrait), 9:16 (TikTok, Reels). If you need a specific aspect ratio, use the image cropper to crop to that ratio, then resize to the exact pixel target.

What are megapixels?

Megapixels = width × height ÷ 1,000,000. A 4000×3000 pixel image = 12 megapixels. More megapixels means more detail and larger file sizes. Smartphone cameras range from 12 MP (iPhone SE) to 200 MP (Samsung Galaxy S24 Ultra). For web use, 2–5 MP is more than enough; for large print, you want 10 MP+.

Why is my image file size larger than expected?

A common surprise: a 4000×3000 PNG at full quality can be 20–40 MB even though the JPEG version is 3 MB. This is because PNG uses lossless compression while JPEG uses lossy compression. If your image is larger than needed, use the image compressor to reduce file size, or the image resizer to reduce dimensions.

Can I check multiple images at once?

Yes — drop multiple images at once and all their dimensions appear in the list. Useful for auditing a batch of assets before uploading to a website or app.

How do I check image dimensions on Windows?

Right-click the image file in File Explorer → Properties → Details tab. Under the Image section you'll see Width and Height in pixels, along with DPI and bit depth. Alternatively, open the image in Paint and the dimensions appear in the status bar at the bottom. This tool is faster for quick checks on any device without opening the file.

How do I check image dimensions on Mac?

Open the image in Preview, then go to Tools → Show Inspector (or press Cmd+I). The General tab shows pixel dimensions, file size, color space, and DPI. You can also right-click any image file in Finder → Get Info → More Info section. This tool is useful when you want dimensions without opening an app, especially on mobile.

How do I find image dimensions in CSS?

Use JavaScript to read the natural pixel dimensions of a loaded image: img.naturalWidth and img.naturalHeight return the original pixel size regardless of how the image is styled on screen. The CSS properties width and height only tell you the rendered display size, not the actual pixel dimensions of the image file.

What are common social media image dimensions?

Key sizes to know: Facebook post 1200×630px, Facebook cover 820×312px, Instagram square 1080×1080px, Instagram story 1080×1920px, Twitter/X post 1200×675px, Twitter/X header 1500×500px, LinkedIn post 1200×627px, LinkedIn banner 1584×396px, YouTube thumbnail 1280×720px, YouTube channel art 2560×1440px. If your image doesn't match a target, use the image resizer to adjust dimensions.

What is DPI and how does it relate to pixels?

DPI (dots per inch) describes how many pixels are packed into one inch of a printed image — it only matters for print, not for screens. Web and screen images use 72–96 DPI by convention, but the DPI value has no effect on how the image looks on a monitor. For print you typically need 300 DPI: a 3000×2000 pixel image at 300 DPI prints at 10×6.67 inches. A 6000×4000 pixel image at 300 DPI prints at 20×13.3 inches. This tool shows the DPI metadata stored in the file alongside the pixel dimensions.