Print Size Calculator
How large an image prints at any DPI, the biggest print at 300, 150 and 72 DPI, and the pixels needed for A4, A3, Letter, photo and poster sizes.
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About this toolWhat is the Print Size Calculator?
An image file has pixels, not inches. How big it prints depends on how many of those pixels you spread over each inch of paper. This calculator divides one by the other: a 6000 x 4000 photo at 300 DPI makes a 20 x 13.3 inch print, the same file at 150 DPI makes a 40 x 26.7 inch poster. Enter your image's pixel dimensions and a target resolution and it gives the print size in inches or centimetres, the largest print at the three standard resolutions, and the megapixel count.
It also works the other way. Type a print size and DPI to see how many pixels you need, or check the paper table, which lists ISO 216 A-series sizes from A6 to A0, US Letter, Legal and Tabloid, and common photo and poster sizes. For each it shows the pixels required, the resolution your image would actually reach if it filled the sheet, and whether that meets your target.
- Print size in inches and cm at any DPI, plus the largest print at 300, 150 and 72 DPI
- Pixels and megapixels needed for any print size and resolution
- ISO 216 A0 to A6, US Letter, Legal, Tabloid, photo and poster sizes with fit check
- Achieved DPI for each paper size, allowing rotation and cropping to fill
- Copy results and share link, all in the browser
How to use the Print Size Calculator
- Enter the image width and height in pixels and the print resolution in DPI.
- Choose inches or centimetres for the print size.
- Read the print size at your DPI and the largest print at 300, 150 and 72 DPI.
- Under "Pixels needed", type a print size and DPI to see the pixel dimensions and megapixels required.
- Use the paper table to check A-series, US and photo sizes, with the resolution your image would reach on each.
Worked examples
24 megapixel camera
Input
6000 x 4000 px at 300 DPI
Output
20 x 13.33 in (50.8 x 33.9 cm); 40 x 26.67 in at 150 DPI
Plenty for any photo print, and a 24 x 36 in poster still gets 167 DPI on the short side.
Phone photo on A4 and A3
Input
4032 x 3024 px (12.2 MP)
Output
A4: 345 DPI, fits. A3: 244 DPI, below 300
A3 at 244 DPI still looks good at arm's length; the 300 DPI target matters most for small prints viewed close up.
Pixels for a poster
Input
24 x 36 in at 150 DPI
Output
3600 x 5400 px (19.4 MP)
At 300 DPI the same poster would need 7200 x 10800 px, beyond most cameras, which is why poster work uses lower resolutions.
Background and insight
The relation is simple: inches = pixels / DPI, and pixels = inches x DPI. Print shops and photo labs usually ask for 300 pixels per inch for prints held in the hand, because at a reading distance of about 30 cm that is close to the detail the eye can resolve. Large prints are viewed from further away, so 150 DPI is generally fine for posters and much lower works for banners seen across a room.
ISO 216 defines the A-series: A0 has an area of one square metre with sides in the ratio 1 : √2, and each smaller size halves the one before, so A4 is 210 x 297 mm. At 300 DPI an A4 sheet needs 2480 x 3508 pixels and A3 3508 x 4961. US Letter is 8.5 x 11 inches, or exactly 2550 x 3300 pixels at 300 DPI.
The DPI value stored in a JPEG or PNG is only metadata; changing it does not change the pixels. What matters is the pixel count and the size you print at. Printer specifications such as 1200 or 4800 dpi count ink droplets, which is a different measure from image pixels per inch.
Common use cases
Ordering photo prints
Check the largest print a photo can make before ordering from a lab or online service.
Preparing print artwork
Set up flyers, posters and A-series documents at the right pixel size before you start designing.
Checking supplied images
Confirm whether a client's logo or photo has enough pixels for the size it will be printed.
Camera and scanner choices
Work out the megapixels or scan resolution needed for a target print size.
Tips and limitations
- Do not rely on the DPI value in the file properties; it is only a label. Look at the pixel dimensions.
- Upscaling with software adds pixels but cannot add real detail. AI upscalers can help but may invent texture.
- Leave room for bleed (usually 3 mm per edge) on anything printed to the edge of the sheet.
- If the image and paper have different aspect ratios, part of the image is cropped or white borders appear. The table assumes cropping to fill.
- Fine text and line art benefit from higher resolution than photos; 600 DPI or vector artwork is common for small type.
Frequently asked questions
How big can I print a photo at 300 DPI?
Divide each pixel dimension by 300. A 6000 x 4000 pixel image prints at 20 x 13.3 inches; a 4032 x 3024 phone photo prints at 13.4 x 10.1 inches.
How many pixels is A4 at 300 DPI?
2480 x 3508 pixels. A4 is 210 x 297 mm, or 8.27 x 11.69 inches, and each inch needs 300 pixels.
Is 150 DPI good enough for printing?
For posters and large prints viewed from a metre or more, yes. For photos and documents read at arm's length, 300 DPI looks noticeably sharper.
How many megapixels do I need for an 8x10 print?
At 300 DPI an 8 x 10 inch print needs 2400 x 3000 pixels, which is 7.2 megapixels. Most phones and cameras exceed that.
Does changing the DPI of an image make it better quality?
No. Changing only the DPI tag leaves the pixels the same and just changes the default print size. Quality depends on how many pixels you have for the size you print.
How do I convert pixels to inches?
Inches = pixels / DPI. 3000 pixels at 300 DPI is 10 inches; at 150 DPI it is 20 inches. For centimetres multiply the inches by 2.54.
Is there an in-depth guide to the Print Size Calculator?
Yes. “Print Resolution: How Many Pixels You Need at 300 DPI” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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