Pixels to Physical Size Converter
Convert pixels to inches, centimetres, or millimetres and back. Enter your DPI to get exact print dimensions. Two-way conversion with a handy reference table.
Input
Result
Common Conversions Reference
| Scenario | Pixels | DPI | Size (mm) | Size (in) |
|---|---|---|---|---|
| Screen 96 DPI | 96 | 96 | 25.40 mm | 1.00 in |
| Web 150 DPI | 150 | 150 | 25.40 mm | 1.00 in |
| Print 300 DPI | 300 | 300 | 25.40 mm | 1.00 in |
| High Quality 600 DPI | 600 | 600 | 25.40 mm | 1.00 in |
| HD Width 1920px at 96 DPI | 1920 | 96 | 508.00 mm | 20.00 in |
| A4 Width 2480px at 300 DPI | 2480 | 300 | 209.55 mm | 8.25 in |
How to Convert Pixels to Inches, Centimetres or Millimetres
The maths is simple: physical size = pixels divided by DPI (dots per inch). 300 pixels at 300 DPI is 1 inch; 1500 pixels at 150 DPI is 10 inches; 2480 pixels at 300 DPI is exactly A4 width (8.27 inches, 21cm, 210mm). The DPI tag in the file controls the output size at the print stage; the same 1500-pixel image prints at 5 inches if labelled 300 DPI, or at 10 inches if labelled 150 DPI. The calculator handles both directions: enter pixels plus DPI to get physical size in mm, cm and inches; or enter physical size and DPI to get the pixel count needed.
Different uses need different DPI. Web display ignores DPI entirely (browsers measure in CSS pixels, never paper inches), so the figure is purely metadata for any image used online. Photo lab prints standardise on 300 DPI for sizes up to A3, dropping to 240 DPI for A2 and 200 DPI for posters viewed at a metre or more. Newspaper printing uses 150 DPI because the paper itself cannot reproduce finer detail. Office laser printers run at 600 DPI on the printer side but typically receive 300 DPI source files because beyond that the file size grows with no visible benefit.
Common Pixel-to-Print Conversions at 300 DPI
| Pixels | Inches | Centimetres | Common Use |
|---|---|---|---|
| 1800 x 1200 | 6 x 4 | 15.2 x 10.2 | Standard photo print |
| 2100 x 1500 | 7 x 5 | 17.8 x 12.7 | Large photo print |
| 2480 x 3508 | 8.27 x 11.7 | 21 x 29.7 | A4 page |
| 3000 x 2400 | 10 x 8 | 25.4 x 20.3 | 8x10 inch print |
| 3508 x 4961 | 11.7 x 16.5 | 29.7 x 42 | A3 page |
| 4961 x 7016 | 16.5 x 23.4 | 42 x 59.4 | A2 poster |
When the DPI Setting Actually Matters
The DPI tag matters when the destination uses it: print labs, professional layout software (InDesign, QuarkXPress, Affinity Publisher), and some print-on-demand platforms (Printful, Society6) all read the DPI metadata to position the image at the intended physical size. A file labelled 72 DPI sent to a print lab will get rejected even if the pixel count is sufficient, because the lab's prepress software treats it as a screen-only file. Use the calculator to confirm both the pixel count and the implied physical size before sending files anywhere print-related.
DPI does not matter for web, email, social media, app icons, or any digital-first use case. Browsers and apps measure in CSS pixels and ignore the DPI tag completely. A 1200x630 image labelled 72 DPI displays exactly the same as the same file labelled 300 DPI on every website. If a designer says 'send me images at 300 DPI' and the destination is a webpage, they are repeating something they heard in design school but it does not change the output. For physical print, follow the [image DPI changer](/image-dpi-changer) to update metadata without resampling, or pair with the [megapixel calculator](/megapixel-calculator) to check whether a pixel count is enough for the intended print size.
Frequently Asked Questions
How many pixels are in an inch?
It depends on the DPI setting. At 72 DPI, 1 inch is 72 pixels. At 96 DPI (the Windows default), 1 inch is 96 pixels. At 300 DPI (the print standard), 1 inch is 300 pixels. There is no universal pixels-per-inch figure; the conversion always requires you to specify DPI. For screen display, 96 DPI is the historical figure but modern high-resolution displays use 144, 192 or higher actual pixel densities.
How do I convert centimetres to pixels?
Convert centimetres to inches first (divide by 2.54), then multiply by DPI. 10cm at 300 DPI: 10/2.54 = 3.937 inches, then x 300 = 1181 pixels. The calculator does this in one step when you enter centimetres and DPI directly. Most A-series paper sizes are easier to remember in pixels at 300 DPI: A4 is 2480 x 3508, A3 is 3508 x 4961, A5 is 1748 x 2480.
Why does my A4 print come out smaller than expected?
Either the file is labelled at a higher DPI than the lab is using (so the physical size shrinks), or the print software is auto-fitting to the page with margins. A 1500x2100 image labelled 300 DPI prints at 5x7 inches, not A4. To fill A4 you need at least 2480x3508 pixels at 300 DPI. Check the DPI metadata before sending to print, and confirm the lab does not auto-scale to fit margins.
What's the difference between DPI and PPI?
Strictly speaking, DPI (dots per inch) refers to printer output and PPI (pixels per inch) refers to digital images, but the terms are used interchangeably in practice. Camera and image software use 'DPI' even though they really mean PPI. Unless you are deep in the prepress industry, treating them as the same value is fine. The calculator uses 'DPI' throughout to match what most users are searching for.
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