Edited by Jason Parnell-Brookes
November 28, 2019
Standard Picture Sizes
Discover standard photo sizes and how best to optimize your photographs for print and web.
Why Resize Photos?
There are two reasons why we might want to resize photographs: to print them or to display them online. Small photos (i.e. postcard size) will need to be printed differently to big photos (i.e. poster size), and the quality of the paper also impacts what resize settings we use. The same is true for online use of digital photos, where height and width are restricted by the size and shape of the viewing device and the quality of said image impacts how fast or slow it loads on computers and webpages.
Both print and online photo use are almost identical in every way, but each have their own specific requirements and limitations. Both print and online images are made up of height and width, and contain many points of colour to represent what’s in the photograph. For print, these points of colour are called ‘dots’, in digital photos they’re referred to as ‘pixels’. The dots typically consist of four colours: Cyan; Magenta; Yellow and Key (Black), aka CMYK. Whereas each digital pixel is made from combining three colours: Red; Green and Blue (RGB). These dots and pixels combine together to create a photograph.
However, neither dots nor pixels have a standardised size. So that means the resolution of an image (how many dots/pixels that make up a photo) is determined by how many dots/pixels are along its width and its height, like this: 1800x1200. The more you have, the greater the image detail.
Standard Photo Print Sizes
Normal photo print sizes are measured in inches or millimetres because they’re physical, tangible items. The print resolution (measured in Dots Per Inch) is determined by the absorption of the paper a photo is printed on. If paper is coarse and the ink bleeds easily then a lower resolution of, say, 100 DPI may be all that’s required because the bleeding limits how fine the details are rendered. However, if paper is smoother and doesn’t allow the ink to run as much then a finer resolution can be used. For example, a broadsheet newspaper might be printed at 100 DPI, whereas on glossy photo paper or in glossy magazines it could be increased to 300 DPI to give higher definition.
Standard picture sizes are determined by historical print reproduction and are generally regarded as being measured in inches. Common sizes are as follows: 8x10, 7x5, 6x4, and 2x3. Square crop photos can also be used, for example the smallest usually being 1x1.
Standard Photo Sizes for Web
Digital photo sizes are measured in pixels. This is because regular viewing devices (laptops, tablets and smartphones) all have screens made up of individual pixels with red, green and blue lights making each pixel on the screen. The density of the pixels per inch is known as the resolution, and often abbreviated to PPI. Like in printing, a higher PPI equals finer detail in image reproduction.
However, since pixels don’t have an average size, a 50” screen could have the same resolution as a 12” screen. That makes resizing photos a little more tricky as they need to display easily (and load quickly) on any device. Digital photo resolution is measured at 72 PPI universally across any device, so the only changing factor when it comes to preparing your photos for online use is the length and width of the image and how much compression is used to make the file small enough to load quickly on slow internet speeds. Arguably, it’s the file size of a photo that is ultimately more important than the resolution. This is because websites with big files take longer to load. Longer loading times affect search engine optimization which means they may rank lower in the list on search engines such as Google.
Online, photographs do not have any restrictions on size or shape, but many websites will use standard aspect ratio crops on images. 16:9 dimensions are common and display in a letterbox shape, regardless of the resolution of the images. Instagram, for example, run 1:1 crops making square photos and currently use a resolution of 1080x1080 pixels, although they also allow for landscape and portrait orientations of rectangular photos now, too.
How to Convert Between Print and Web
It’s easy to calculate sizes between print and web use by using multiplication as long as we know the DPI/PPI required. For example, in a 6x4 image that we want to print at highest quality we take each side and multiply it by the resolution. Here we’ll use 300 DPI/PPI. So, 6x300 = 1800 and 4x300 = 1200, so a 6x4 photo at 300 DPI = 1880x1200 pixels in size. The reverse is true for calculating from web to print, just divide resolution lengths by pixel density e.g. 1800/300 = 6 inches.
The International Standards Organization is a governing body that regulates standard print sizes and are categorized into A, B and C Series. However, because A Series is most commonly used, below you’ll find a handy conversion guide to convert pixels to inches. All sizes are converted at a resolution of 300 DPI/PPI.
Convert Pixels to Inches
|Print Size (inches)||File Size (pixels)|
Check the following conversion chart to learn about A4 paper size in pixels.
Convert ISO Standard to Pixels (resolution: 300DPI/PPI)
|ISO Standard||File Size (pixels)|
A4 size is 210mmx297mm (8.27”x11.69”) in pixels at 300 DPI = 2480 x3508 or 72 DPI = 595 x 842
Image resizing is necessary if the chosen photo doesn’t fit your intended printing size. Let’s figure out what to do if:
- An image is larger than the printing size and has the same proportions
Resize the image and constrain proportions.
- An image is larger than the printing size and has different proportions
Choose the part of the picture you want to print and crop the image.
- An image is smaller than the printing size
Use the resizing tool to make the photo bigger. Note that, in this case, the image quality deteriorates.
Resize Pictures in Movavi Photo Editor
- Click the Resize tab.
- Select or enter the necessary image size:
- Enter the dimensions into the Width and Height boxes. Click the lock icon to disable the Constrain proportions option if needed. You can also change the measurement unit in the box on the right.
- Choose from preset sizes.
- Click Another size in the bottom of the panel to view more size options.
Crop Pictures in Movavi Photo Editor
- Open the Crop tab.
- Specify the size or proportions you want on the right-hand panel:
- Enter the width and height into the corresponding boxes.
- Select suitable proportions from the list.
- Adjust a crop frame manually. Move its edges with your mouse.
Jason Parnell-Brookes is an internationally award-winning photographer. He won Gold in the Nikon Photo Contest 2018/19 and was named Digital Photographer of the Year in 2014. He is also a Masters graduate, qualified teacher and writer.
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