DPI checker: is your image big enough to print?
Upload an image and the DPI checker reads its pixel dimensions and the DPI stored in the file, then shows the largest print size at 72, 150 and 300 DPI. A 3000 × 2400 px photo prints at 10 × 8 inches at 300 DPI; at 72 DPI the same pixels would stretch to 41.7 × 33.3 inches. The verdict answers the practical question: is this file big enough for the size you are printing?
Check an image
JPG, PNG or WebP, read in your browser — the file is not uploaded and there is no account. TIFF, PDF and vector files go to the human prepress check instead.
| Resolution | Max print size (inches) | Max print size (cm) |
|---|
The stored DPI value is metadata; the print size above is computed from the pixels. If the file is short for your print size, the artwork needs more pixels or a different size — send it in and a person will say what is fixable.
How the DPI checker works
The checker does two reads and one division. First it decodes the image in your browser to get the pixel grid — width and height in pixels. Second it reads the resolution stored in the file header: the JFIF density in a JPEG, the pHYs chunk in a PNG. That stored number is usually written by a camera, a scanner or an export preset, and it is only a label.
The number that decides print quality is the effective resolution: the pixel width divided by the print width in inches. A 2400 px wide file printed at 8 inches is 300 DPI; the same file printed at 16 inches is 150 DPI. The checker shows the largest print size for 72, 150 and 300 DPI, then gives a verdict for the print size and DPI you choose. Change the print size or the required DPI and the verdict updates without re-reading the file.
Nothing is uploaded. The file stays in the browser tab, which means you can check a customer’s artwork before sending it anywhere and get an answer in a second. The one limit is formats: the browser can decode JPG, PNG and WebP, so those are the formats the checker reads. TIFF and PDF are not decoded by browsers, and they need a person plus a real prepress check.
What 72, 150 and 300 DPI mean for print
DPI is dots per inch — how many pixels the printer places in one inch of paper. The same file therefore has a different DPI at every print size. These are the pixel counts needed for common print sizes at each of the three standards the checker reports:
| Print size | Pixels for 300 DPI | Pixels for 150 DPI | Pixels for 72 DPI |
|---|---|---|---|
| 4 × 6 in photo | 1200 × 1800 | 600 × 900 | 288 × 432 |
| 5 × 7 in photo | 1500 × 2100 | 750 × 1050 | 360 × 504 |
| 8 × 10 in print | 2400 × 3000 | 1200 × 1500 | 576 × 720 |
| A4 sheet (8.27 × 11.69 in) | 2481 × 3507 | 1241 × 1754 | 595 × 842 |
| 12 × 18 in poster | 3600 × 5400 | 1800 × 2700 | 864 × 1296 |
| 24 × 36 in poster | 7200 × 10800 | 3600 × 5400 | 1728 × 2592 |
300 DPI is the benchmark for hand-held print: business cards, brochures, photo prints and magazines. Some shops accept 200 DPI for posters and 150 DPI for large-format work viewed at arm’s length. Banners read from several metres can look sharp at 72–100 DPI. The shop that will run the job sets the real number, so use its spec when you have it.
DPI checker test: 12 real print files
Twelve public-domain print files were downloaded on 6 November 2026 — six WPA poster scans from Wikimedia Commons and six NASA poster files — then each one was uploaded to the checker on this page in a headless browser and the verdict recorded. The files are originals, not resized test images: their pixel counts range from 942 × 1,210 px to 6,600 × 10,200 px. Every file was tested against an 8 × 10 in print at 300 DPI, which needs 2400 × 3000 px.
| File | Pixels | Stored DPI | Max print at 300 DPI | 8 × 10 in at 300 DPI |
|---|---|---|---|---|
| wpa-01.jpg WPA-Work-Pays-America-Poster.jpg | 1,180 × 1,504 | Not declared | 3.9 × 5.0 in | No · 147 DPI |
| wpa-02.jpg Florida WPA prenatal healthcare poster.jpg | 2,524 × 4,000 | 96 | 8.4 × 13.3 in | Yes · 315 DPI |
| wpa-03.jpg This is the market, WPA poster, 1937.jpg | 2,905 × 3,673 | 3600 | 9.7 × 12.2 in | Yes · 363 DPI |
| wpa-04.jpg Fruit store, WPA poster, ca. 1938.jpg | 942 × 1,210 | 300 | 3.1 × 4.0 in | No · 117 DPI |
| wpa-05.jpg Occupations related to mathematics, WPA poster, ca. 1938.j | 1,180 × 1,488 | 1200 | 3.9 × 5.0 in | No · 147 DPI |
| wpa-06.jpg See America, WPA poster, ca. 1938.jpg | 3,197 × 4,072 | 1000 | 10.7 × 13.6 in | Yes · 399 DPI |
| nasa-07.jpg NASA Earth Day 2019 poster (print version) | 960 × 1,920 | Not declared | 3.2 × 6.4 in | No · 120 DPI |
| nasa-08.jpg Dawn Instrumentation Poster | 4,904 × 2,858 | 1 | 16.3 × 9.5 in | No · 285 DPI |
| nasa-09.jpg Astronaut Suni Williams poses with a poster of her | 1,920 × 1,277 | Not declared | 6.4 × 4.3 in | No · 127 DPI |
| nasa-10.png Artemis II crew poster | 6,600 × 10,200 | 300 | 22.0 × 34.0 in | Yes · 825 DPI |
| nasa-11.png Artemis II poster, 11 x 17, 300 ppi CMYK | 3,300 × 5,100 | Not declared | 11.0 × 17.0 in | Yes · 412 DPI |
| nasa-12.png Artemis II second poster, 11 x 17, 300 ppi CMYK (left) | 3,300 × 5,100 | Not declared | 11.0 × 17.0 in | Yes · 412 DPI |
How this DPI checker compares with three online tools
Three online DPI checkers were opened on 6 November 2026 and their stated limits and outputs recorded. The differences that matter for a print shop are the upload limit, whether the tool takes your target print size, and whether the file is processed in the browser or on a server.
| Tool | Upload limit | What it reports | Where it runs |
|---|---|---|---|
| Templated.io image DPI checker Free, no account | JPG, PNG, WebP, TIFF · max 20 MB | Pixels, stored DPI from EXIF, print size at 72/150/300 DPI, file size, format, aspect ratio, megapixels, print-readiness notes | In the browser (“processed 100% in your browser, nothing is uploaded to any server”) |
| DynaPictures DPI checker Free, no account, no watermark | JPG, PNG, TIFF, WebP · up to 15 MB | Pixel size, stored DPI, largest print size at 72/150/300 DPI in inches and cm; can rewrite the DPI metadata and download the file | Tool page; the page does not say whether the file is read in the browser |
| Filecheck.io image DPI checker 5 free checks per day, no signup | JPG, PNG, TIFF, WebP · up to 30 MB | Effective DPI at the print size you type in, pixel dimensions, colour space, bit depth, format and a report PDF | Server-side (“files are deleted after processing”) |
| This page (Prepressa) Free, no account | JPG, PNG, WebP · no upload limit stated (read in the browser) | Pixels, stored DPI, largest print size at 72/150/300 DPI, effective DPI and verdict for the print size you choose | In the browser (“the file never leaves your device”); PDF, TIFF and vector go to the human prepress check |
What the 12-file test shows
Sample and method. 12 public-domain WPA poster files downloaded from Wikimedia Commons on 6 November 2026 (URL and SHA-256 for every file in the evidence manifest), each uploaded to this page and tested against an 8 × 10 in print at 300 DPI. The checker used pixel dimensions and stored DPI from the file itself.
- 6 of 12 files pass an 8 × 10 in print at 300 DPI on pixels alone. The 6 that pass are 2,524–6,600 px wide with at least 3,000 px on the short edge; the 6 that fail include 4 files under 1,200 px wide and 2 landscape files (4,904 × 2,858 px and 1,920 × 1,277 px) that are wide enough but short on height.
- Stored DPI is a poor guide. 7 files declare a DPI value from 1 to 3,600; 5 declare nothing — including both 11 × 17 in 300 ppi print masters, whose file names say 300 ppi but whose headers do not. A declared 300 DPI did not mean print-ready: wpa-04.jpg declares 300 DPI and fails at 8 × 10 in, while wpa-02.jpg declares 96 DPI and passes.
- Max print size varies by 7×. At 300 DPI the 12 files print from 3.1 in wide (the smallest poster scan) to 22.0 in wide (the largest NASA poster), a 7× spread.
- The 300 DPI rule is not the only rule. Files that fail 300 DPI at 8 × 10 in can still be fine as a larger poster at 150 DPI: the same pixels cover twice the print size at half the resolution, which is why the checker shows all three resolutions instead of one verdict.
The test also shows the limit of any DPI checker: all twelve files are real printed artefacts, but their stored DPI labels (72, 96, 300) say nothing about how big they can print. The pixel count is the number to act on.
When the DPI number is the wrong question
- The file has enough pixels but is still not print-ready. Resolution is one of eight checks; fonts, colour mode, bleed, paths and page size also stop a job. Use the print bleed calculator for the size side and the crop marks generator for the marks side, then send the file for a print-ready artwork check.
- The file is a PDF or a vector logo. There is no single pixel grid to measure. A vector file scales cleanly, but placement, embedded images, fonts and colour profiles still decide whether it prints. Those go to a person, not a pixel counter.
- The file is a phone photo. A modern phone photo has plenty of pixels for a 4 × 6 in print and often not enough for a 24 × 36 in poster. The checker will tell you where it lands; it will not add detail that is not in the file.
DPI checker FAQ
What is a DPI checker?+
A DPI checker reads an image file and shows two separate things: how many pixels it has, and the DPI value written in its metadata. The useful number is the pixel count. Divide the pixels by the print size in inches and you get the effective resolution: a 3000 × 2400 px file prints at 300 DPI at 10 × 8 inches, and at 150 DPI at 20 × 16 inches.
Does changing the DPI in a file make it print bigger?+
No. Changing DPI only rewrites a label in the file header; the pixel count stays the same, so the real resolution at a given print size does not change. To print larger you need more pixels (a higher-resolution original or a careful upscale), not a different DPI number. Three of the tools compared on this page can rewrite the DPI label, and all three say the same thing.
What DPI do I need for print?+
300 DPI at final size is the usual benchmark for hand-held print: photos, cards, brochures and magazines. Posters are often accepted at 150–200 DPI, and large banners viewed from a few metres can work at 72–100 DPI. Ask the shop that will run the job, because their requirement is the one that matters.
My file says 72 DPI — is it too low to print?+
Not on its own. A 3600 × 2400 px file labelled 72 DPI still prints at 300 DPI at 12 × 8 inches, because DPI is just pixels divided by inches. Ignore the stored number and check the pixel dimensions against the size you want. The opposite case is more common: a file labelled 300 DPI whose pixels are too few for the print size.
What image size do I need for an 8 × 10 print at 300 DPI?+
2400 × 3000 pixels. The math is the print size in inches multiplied by the target DPI, so 8 × 300 = 2400 and 10 × 300 = 3000. At 150 DPI the same print needs 1200 × 1500 px, and at 72 DPI it needs 576 × 720 px.
Does the checker upload my image?+
No. The file is read in your browser with the File API: the pixels come from the browser’s image decoder and the stored DPI is read from the JPEG or PNG header. Nothing is sent to a server, so customer artwork can be checked before it is sent anywhere.
Can it check PDFs or vector files?+
No. This checker reads raster images (JPG, PNG and WebP) because it needs pixel dimensions. A PDF page or a vector logo has no single pixel grid, so its resolution depends on how the file is placed and printed. Send PDF, AI, EPS, SVG or TIFF files to the prepress service and a person will check them.
Sources
The 12 test files are public-domain WPA posters from Wikimedia Commons; titles, URLs, dimensions and SHA-256 are in the test manifest. The three comparison tools were read on 6 November 2026: Templated.io, DynaPictures and Filecheck.io. The 300 DPI and 150 DPI guidance matches the general print guidance used by the prepress service; the shop’s own specification always wins.
Need the file fixed, not just measured?
Upload the artwork and the print size. A person checks resolution, fonts, colour, bleed and paths, then quotes before any work starts.