Print Size & PPI Calculator
Turn pixel dimensions and DPI into exact print sizes — or work backwards from a print size to find the DPI or pixels you need. Instant answers, zero uploads.
🔒 Private by design — your files never leave this browser. No uploads, no accounts, no tracking of your images. (This calculator is pure math: nothing is sent anywhere, because there is nothing to send.)
Example values shown — adjust to your files.
Heads up: this is a calculator — it works out the numbers but doesn't open, edit, or save image files.
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The reference badge reflects the DPI number only — it can't inspect your photo for blur, heavy compression, or upscaling.
Common print sizes — pixel targets
Click a row to load its 300 DPI pixel values into the calculator above. The 150 DPI column is the usual target for posters and anything viewed from a few feet away.
| Print size | Pixels @ 150 DPI | Pixels @ 300 DPI |
|---|---|---|
| 4 × 6 in | 600 × 900 | 1200 × 1800 |
| 5 × 7 in | 750 × 1050 | 1500 × 2100 |
| 8 × 10 in | 1200 × 1500 | 2400 × 3000 |
| 11 × 14 in | 1650 × 2100 | 3300 × 4200 |
| A4 (8.27 × 11.69 in) | 1240 × 1754 | 2480 × 3508 |
| 12 × 18 in poster | 1800 × 2700 | 3600 × 5400 |
| 24 × 36 in poster | 3600 × 5400 | 7200 × 10800 |
DPI by use case
- Photo print — 300 DPI. Anything you will hold in your hands or view up close: 4×6, 5×7, 8×10, A4. This is the professional standard for crisp prints.
- Poster — 150 DPI. Viewed from a few feet away, 150 DPI looks sharp while keeping file sizes manageable. A 24×36 poster at 150 DPI needs only 3600 × 5400 pixels.
- Large banner — 72–100 DPI. Billboards, trade-show backdrops, and banners viewed from many feet away. Viewing distance does the work that resolution would.
- Screen — 72 DPI. A legacy convention from early monitors; what actually matters on screen is the pixel dimensions, not the DPI value. A 1920 × 1080 image is the same on screen at 72 or 300 DPI.
- Scanning — match your target print DPI. Decide the final print size and DPI first, then scan at a resolution that delivers those pixels. Doubling the print size means doubling the scan DPI.
How to use this DPI converter
- Pick what you want to find. Print size is the classic question ("how big will this print?"), but you can also solve for the DPI an existing print achieves, or the pixel dimensions a target print requires.
- Enter the numbers you know. Pixel dimensions are in your image file's properties; DPI is whatever the printer or print shop asks for (300 is the safe default).
- Read the results. Print size is shown in both inches and centimeters, and the resolution reference tells you at a glance which industry DPI band the result falls in.
The formulas, explained
Every conversion on this page is one of three rearrangements of the same relationship: pixels = inches × DPI. There is no hidden magic — these are exact arithmetic, which is why a calculator beats mental math once the numbers get awkward.
To find how large a file prints, divide each pixel dimension by the DPI. A 6000 × 4000 pixel photo at 300 DPI gives 6000 ÷ 300 = 20 inches wide and 4000 ÷ 300 = 13.33 inches tall. Multiply inches by 2.54 for centimeters (50.8 × 33.9 cm) or by 25.4 for millimeters.
To find the effective resolution of an existing print, divide pixels by the printed inches. A 2400 × 3000 pixel image printed at 8 × 10 inches yields 300 DPI — comfortably photo quality.
To find how many pixels you need, multiply. An 11 × 14 inch print at 300 DPI needs 3300 × 4200 pixels. This direction is the one people get wrong most often: they buy a "high resolution" file without checking whether it has enough pixels for their print size.
Megapixels are simply total pixels divided by one million: 6000 × 4000 = 24,000,000 pixels = 24.0 MP. Camera makers advertise megapixels, but for printing, the per-side pixel dimensions matter more than the total.
DPI vs PPI: what is the difference?
PPI (pixels per inch) describes pixel density in a digital image or on a display. DPI (dots per inch) describes how many dots of ink a printer deposits per inch of paper. Strictly speaking, your image file has a PPI and your printer has a DPI.
In practice, for everyday photo printing the two are used interchangeably, and that is fine: a 300 PPI file produces exactly the physical size the math above predicts. The confusion mostly causes trouble in two places. First, DPI does nothing on screen — a 1920 × 1080 image displays at the same size at 72 or 300 DPI because screens size images by pixel dimensions (and CSS scaling), not by the DPI number. Second, professional printers often print at much higher hardware DPI (1440, 2880) while still asking for 300 PPI image files; the printer's dot density and your image's pixel density are related but separate numbers.
One more honest note: AI chatbots can recite these formulas for you now, which is worth saying plainly. The reason a dedicated calculator still earns its place is iteration speed — you change one number and every derived value, the quality rating, and the metric conversion update instantly, instead of re-asking a chatbot six times while you compare print sizes.
Resolution reference guide
The reference badge on the results panel places the effective DPI into four bands commonly used across the printing industry. It describes the number, never your actual photo:
- 300 DPI and up — sharp-print reference. The industry's usual reference for prints viewed up close: at normal reading distance the human eye stops resolving individual dots around this density. It describes the number, not your photo — a blurry source is still blurry at 300 DPI.
- 150–299 DPI — poster reference. Fine for posters, photo books, and anything viewed from arm's length or more. Most people cannot tell 150 from 300 DPI on a wall-mounted print.
- 100–149 DPI — large-format reference. Acceptable for large posters and displays viewed from several feet away. Up close you will see softness.
- Below 100 DPI — draft only. Only appropriate for banners and billboards viewed from many feet away. For anything smaller, pick a smaller print size or find a higher-resolution source image.
A low rating is not a dead end — it is information. Shrink the print size, accept a lower DPI target for a poster, or start from a bigger file. What upscaling software cannot do is invent detail that was never captured, so treat "enhanced" files with skepticism when the math says the pixels are not there.
Frequently asked questions
How do I calculate print size from pixels and DPI?
Divide each pixel dimension by the DPI. A 6000 × 4000 pixel image at 300 DPI prints at 20 × 13.33 inches. Multiply inches by 2.54 for centimeters. The calculator above does all three conversions at once.
What is the difference between DPI and PPI?
PPI (pixels per inch) belongs to the digital image; DPI (dots per inch) belongs to the printer. For everyday photo printing they are used interchangeably — a 300 PPI file gives the predicted physical size — but DPI means nothing on screen, where only pixel dimensions count.
What DPI should I use for photo prints?
300 DPI for anything viewed up close (4×6, 5×7, 8×10, A4). 150 DPI is the usual choice for posters viewed from a few feet away. Large banners viewed from far away commonly use 72–100 DPI.
How many pixels do I need for an 8×10 print at 300 DPI?
Multiply print size by DPI: 8 × 300 = 2400 by 10 × 300 = 3000, so 2400 × 3000 pixels. The preset table above lists pixel targets for common sizes at both 150 and 300 DPI — click any row to load it.
What does a low DPI warning mean?
Your pixel count is too small for the requested print size and DPI, so the print would look soft or pixelated up close. Print smaller, accept a lower DPI (fine for posters), or use a higher-resolution image.
Is 72 DPI enough for printing?
Not for small prints viewed up close — 72 DPI will look blurry. But 72–100 DPI is a legitimate professional choice for large banners and billboards, where viewing distance makes individual dots invisible.
How do I match scan resolution to a target print?
Work backwards from the print. A 4×6 inch print at 300 DPI needs 1200 × 1800 pixels, so scanning the original at 300 DPI gives exactly that per inch of original. Enlarging 2× at 300 DPI output requires a 600 DPI scan.