Omikuji Tools Image & Video

Image & Print Size Calculator

Turn an image's pixel count into printed sizes and check it against paper sizes. The reverse calculation and unit converter work without an image.

✨ What it does

  • See an image's pixel size, aspect ratio, megapixels, file size and format at a glance
  • Printed size at 72/150/200/300/350 dpi, in both millimetres and inches
  • Check whether the resolution is enough for 4×6, 5×7, postcard, B5, A4 and A3 (orientation ignored)
  • Work backwards from paper and dpi to the pixels you need, and convert px ⇔ mm ⇔ inch ⇔ pt without an image

🪄 Good for

Before ordering prints

Check that a phone photo has the resolution for a 4×6, 5×7 or A4 print.

Checking artwork for a printer

Confirm the file meets the pixel count the print shop asks for at their dpi.

Setting up a canvas

Work out the pixel dimensions for an A3 poster at 300 dpi before you start designing.

Moving between units

Read a spec written in millimetres as pixels, or a font size in points as millimetres.

🔒 Privacy

The image is decoded inside your browser purely to read its width and height, and is never sent to a server. The file size and format shown come from the file entry on your own device. The shareable URL carries only settings such as resolution and paper size – never the image, which is also never written to localStorage.

❓ FAQ

What dpi should I use?

Anything held in the hand – photo prints, business cards, brochures – is usually 300–350 dpi. Posters of A2 and larger, viewed from a distance, look fine at 150–200 dpi, and banners or signage are often built at 72–100 dpi. Higher dpi means much heavier files, so choose it to match the viewing distance rather than always going as high as possible.

Does the dpi stored inside the file matter?

What decides print quality is the pixel count and the size you print at; the dpi value written into the file is only a hint. The same 3000 × 2000 px image is 300 dpi when printed 10 inches wide and 150 dpi at 20 inches wide. This tool calculates from the pixel count, so the file's own dpi tag does not affect the answer.

What if a paper size says "Not enough"?

You have three options. Print smaller – the "Best dpi for this paper" column tells you the resolution you would actually get. Accept a lower dpi, which is often fine for anything seen from a distance. Or go back and recapture or rebuild the source at a higher resolution. Upscaling does not add detail, so soft edges will remain.

What is the difference between pt and px?

A point is an absolute length, fixed at 1/72 inch, used for print and font sizes. A pixel is just a dot in an image, and its physical size depends on the dpi. 12 pt is always about 4.23 mm, while 12 px is about 4.23 mm at 72 dpi and about 1.02 mm at 300 dpi. When a spec is written in points or millimetres, pick a dpi first and then convert to pixels.

🔗 Related tools

SVG Converter Image Merge Batch Watermark LocalCanvas PhotoBatch Image Converter WebP Converter EXIF Cleaner Local Mask Image to PDF PDF to Image

Load an image (optional)

Drop an image here

Click to choose a file, or paste with Ctrl+V (⌘V). The image is only inspected inside your browser.

Choose an image

Load an image and its pixel count and printable sizes appear here. The reverse calculation and unit converter below work without one.

Reverse: pixels needed for a paper size and dpi

Width needed
- px
Height needed
- px
Megapixels needed
-

Printing a smaller image blown up to this size gives soft or stair-stepped edges.

Unit converter (px ⇔ mm ⇔ inch ⇔ pt)

Unit
dpi
px
-
mm
-
inch
-
pt
-

1 inch = 25.4 mm = 72 pt. A point (pt) is a fixed 1/72 inch used in print and font sizes and has nothing to do with dpi. Only px changes physical size depending on the dpi.

Privacy

The image is decoded inside your browser purely to read its width and height, and is never sent to a server. The file size and format shown come from the file entry on your own device. The shareable URL carries only settings such as resolution and paper size – never the image, which is also never written to localStorage.