Photo Printing: What's the Difference Between 2R, 3R, 4R, and Other Photo Sizes?

18 October 2023 by
Yammy Kong

Whether it's travel memories, family gatherings, or important life moments, we often capture these beautiful moments with cameras or smartphones. However, when it comes to printing photos, you may have questions about different photo sizes like 2R, 3R, 4R, and more. Capture is here to answer that question, providing you with insights into photo sizes and tips for photo printing, helping you preserve your precious memories!

What are the different sizes for printed photos?

Photo size refers to the dimensions of a photo. Common photo sizes include 2R, 3R, 4R, and others. The specifications for different photo sizes are as follows:

  • 2R:2 x 3
  • 3R:3 x 5
  • 4R:4 x 6
  • 4D:4.5 x 6
  • 5R:5 x 7
  • 6R:6 x 8
  • 8R:8 ×10
  • 12R:8 ×12

In addition, larger sizes are available on the market, such as 10x15, 12x18, 20x30, 30x40, and so on. There are also sizes ranging from A3 to A6, but their applications are relatively less common.

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What does photo size "R" mean?

"R" is the unit for photo sizes, which stands for "inch." It represents the length and width of the photo. For example, the size of a 2R photo is 2 inches x 3 inches, and the size of a 3R photo is 3 inches x 5 inches, and so on.

If we convert it to centimetres, 1 inch is equal to 2.54 centimetres (cm). Taking a 4R photo as an example, the size in centimetres would be 10.16 cm x 15.24 cm.

Photo Size Comparison Chart

Here is a photo size comparison chart to help you understand the pixel requirements and file sizes for different sizes. Please note that this chart is for reference purposes only. Different photo printing shops may have different requirements, so please follow the specifications provided by the specific printing shop.

Photo Specifications

Photo Size (cm)

Aspect Ratio

Minimum Pixel Requirement

Recommended File Size


6.4 cm x 8.9 cm


480 X 640



8.9 cm x 12.7 cm


960 X 1280



10.2 cm × 15.2 cm


1024 x 1280



11.4 cm × 15.2 cm 


1024 x 1280



12.7 cm × 17.8 cm


1200 x 1600



15.2 cm × 20.3 cm


2032 x 1524



20.3 cm × 25.4 cm


2032 x 2540



25.4 cm × 30.5 cm


2032 x 3048


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How to choose a photo size? 4R VS 4D?


Traditional film photos have an aspect ratio of 2:3, which is commonly seen in the 4R size ratio. However, with the popularity of digital cameras, digital photos have an aspect ratio of 4:3, which corresponds to the 4D photo size ratio. If you print a digital photo with a 4:3 aspect ratio using the 4R size, there will be white borders. To avoid the white borders, a portion of the image may be cropped.

Therefore, it is essential to choose the appropriate size. You can pay attention to the aspect ratio of the photos you capture and then select the suitable size accordingly. If you capture photos with a digital camera, it is recommended to print them in 4D size. If you capture photos with a DSLR camera, you can opt for the 4R size.

Tips for Photo Printing


Before printing your photos, it is recommended to consider the following tips to ensure the best quality:

  • Pixel Requirements: Ensure that your photos meet the pixel and file size requirements specified by the printing shop to avoid any loss of quality during the printing process.
  • Ratio of Photos: Make sure that the aspect ratio of your photos matches the printing size to avoid cropping or distortion.
  • Image Editing Software: If the photo's aspect ratio doesn't match or if you want to make adjustments to brightness, contrast, or other aspects, you can make those edits yourself before printing or seek assistance from the printing shop.
  • Clear Instructions: Provide clear instructions to the printing shop, such as requesting to preserve white borders, specifying colour or brightness adjustments, and any other desired modifications, to ensure that the final prints meet your expectations.
  • Backup in advance: To protect your precious photos, it is recommended to make a backup on your computer, external hard drive, or cloud storage before printing to prevent loss or damage.

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*This article is brought to you by Capture HK.

Capture HK is the premier analogue media digitisation company in Hong Kong.

Capture HK's business covers photographs, photo album, slide digitisation, videotapes digitisation, including VHS, S-VHS, VHS-C, S-VHS-C Hi-8, Video8, Digital8, DV, DVCAM, MiniDV, DVC and digital media digitisation, including Secure Digital (SD), Smart Media (SM), MultiMediaCard (MMC) Compact Flash (CF), xD-Picture Card, Memory Stick, USB Drive, CDROM, DVD.

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