Check the resolution and quality of any image
Is this photo big enough for an A4 print? Will it look sharp as a 4K wallpaper? What JPEG quality was it saved at? The Image Resolution Checker answers in one step. Drop in one image or a whole folder and it reads each file’s header to report width × height, megapixels, aspect ratio (simplified and named), file size, bit depth and colour type, the DPI stored in the file, an estimate of the JPEG quality, and the print size at 150 and 300 DPI.
Each image then gets a plain-language verdict for common uses — an Instagram post, a Full HD screen, a 4K wallpaper, a 6 × 4 in photo print, an A4 page and a passport photo. Batches are listed in a table you can download as CSV. The files are read in your browser and never uploaded.
How to use the Image Resolution Checker
- Drop images onto the upload area or click to choose them — JPG, PNG, WebP, GIF, BMP, TIFF, HEIC and AVIF all work.
- Read the summary for the selected image: pixels, megapixels, aspect ratio, file size, bit depth, JPEG quality, DPI and print sizes.
- Check the “Good enough for…” list: green means ready, amber means usable with a compromise, red means too small.
- Tap any row in the table to see that image’s details.
- Press “Download CSV” for a spreadsheet of every image, or “Copy as table” to paste into Excel or Google Sheets.
Image Resolution Checker features
Reads the file header
Dimensions and bit depth come straight from the JPEG frame header, PNG IHDR, WebP VP8/VP8L/VP8X, GIF, BMP, TIFF tags or HEIC/AVIF ispe boxes — no guessing.
JPEG quality estimate
Compares the quantisation tables with the IJG scale used by most encoders. “Standard tables” means an exact match; otherwise a close estimate is shown.
Named aspect ratios
Simplifies 4032 × 3024 to 4:3, recognises 16:9, 3:2, 4:5 and others, and marks near matches such as 1366 × 768 ≈ 16:9.
Orientation aware
Phone photos stored sideways with an EXIF rotation tag are reported at the size you actually see.
Practical checks
Instagram, Full HD, 4K, 6 × 4 in print, A4 and passport verdicts with the DPI each print would reach.
Batch table and CSV
Check many images at once and export everything for a spreadsheet or an asset audit.
Resolution, megapixels and DPI explained
Resolution is the pixel size of the image, written width × height, e.g. 4032 × 3024. Megapixels is width × height ÷ 1,000,000 — that photo is 12.19 MP. Neither depends on the file format or compression. DPI is only a print instruction stored in the file: dividing the pixels by a DPI gives the print size, so 4032 × 3024 px prints at 13.44 × 10.08 in at 300 DPI or twice that at 150 DPI.
Because DPI is only a label, two files with the same pixels have the same detail whatever DPI they claim. To change the label without touching the pixels use the Image DPI Checker; to work out the pixels a print needs, use the DPI calculator.
Resolution needed for common uses
| Use | Minimum pixels | Notes |
|---|---|---|
| Instagram post | 1080 px wide | Narrower photos are upscaled |
| Full HD screen, 1080p video frame | 1920 × 1080 | 2.07 MP |
| 4K UHD wallpaper | 3840 × 2160 | 8.29 MP |
| 6 × 4 in photo print at 300 DPI | 1800 × 1200 | 2.16 MP; 150 DPI (900 × 600) is the bare minimum |
| A4 print at 300 DPI | 2480 × 3508 | 8.7 MP; 150 DPI is fine for documents |
| Passport photo at 300 DPI | 413 × 531 (35 × 45 mm) or 600 × 600 (2 × 2 in) | Rules on head size and background also apply |
Understanding bit depth, colour type and JPEG quality
- Bit depth: most JPEG, WebP and PNG photos use 8 bits per channel (24-bit colour, 16.7 million colours). PNG and TIFF can store 16 bits per channel for editing headroom; palette PNGs and GIFs store up to 256 colours.
- Colour type: “RGBA” or “+ alpha” means the image has transparency. JPEG cannot store transparency.
- Chroma subsampling: JPEGs usually keep colour at lower resolution than brightness. 4:2:0 is standard for photos; 4:4:4 keeps sharp coloured text and edges.
- JPEG quality: 90–100 is near-lossless, 75–85 is typical for the web, below 60 shows blocky artefacts. A high estimate on a small, soft image usually means it was upscaled or re-saved — quality cannot add detail. To shrink a large file, try the image compressor; to change the pixel size, use the image resizer.
Image Resolution Checker FAQ
How do I check the resolution of an image?
Drop it into this image resolution checker. It shows the width × height in pixels, megapixels, aspect ratio, DPI and print sizes immediately, read from the file’s own header.
Is my photo good enough to print?
Look at the 6 × 4 in and A4 checks. Green means the image reaches 300 DPI at that size, amber means 150–299 DPI (acceptable for many prints), and red means it will look soft or pixelated.
How accurate is the JPEG quality estimate?
For files from libjpeg-based encoders — browsers, many apps and editors — it is usually exact, shown as “standard tables”. Cameras and some editors use their own tables, so the number shown is the closest equivalent on the same 1–100 scale.
Why is the resolution different from what my phone shows?
Some phones store photos sideways and add an EXIF rotation tag. This checker reports the size you actually see and notes the stored size, so the numbers match what your gallery displays.
What aspect ratio is 1366 × 768?
Exactly 683:384, which is within 0.1% of 16:9, so the checker shows it as “≈ 16:9”. Many laptop screens use this resolution.
Are my images uploaded?
No. The files are analysed in your browser and nothing is sent to a server. Because the numbers come from the file headers, HEIC and TIFF files can be checked even if your browser cannot display them.