Image Source Plus / Alamy

What file size do I need for my image?

Getting started…

Before we start you need to know a couple of things about your final image to help determine what file size you’ll need for your image.

The Dimension is the size the image will be when it’s printed.

The Resolution is the amount of detail an image has, the higher the resolution the more detail. It’s normally measured in dpi (dots per inch) and as a rule, it’s 300dpi for print and 72dpi for web. Large format prints, such as billboards, are usually printed at lower resolutions of under 150dpi (although the detail up close will be lower than normal, its real-world application means that this won’t be a problem as they are usually viewed from a distance).

If you’re not sure about either of these it’s worth checking with your designer before you start.

Some more helpful tips…

Using royalty free images

With royalty free images the larger the file size, the higher the cost but don’t let that convince you that buying a smaller size and making it bigger is a good idea. It’s easy to downsize an image without compromising quality, but if you buy an image that’s too small the quality will be affected when you try to make it bigger. It’s like using the digital zoom on your mobile: yes, the subject now fills the frame but the quality has been compromised.

Using mobile images

Mobile photography is a growing trend and with the introduction of iPhone apps like Stockimo, you’re going to start seeing more and more mobile images on stock photography sites. Although the cameras on these phones are amazing and so is the quality of the image, it does sometimes mean that the file size is smaller. It’s an important factor to consider. In many cases, the dimension requirement isn’t that big but you might have some issues if you want to use it on a billboard. See our handy diagram below to help you decide if the image is big enough.

Use the minimum file sizes filter when you search

If you do need a larger file size for your project, use the ‘Image’ dropdown near the top of any search results page to select the minimum file size you’re interested in.

If you’re not sure what file size you need this diagram might help, this is just a guideline of the industry standard sizes so might not match up exactly to the file sizes you see on Alamy. The sizes shown are for an uncompressed JPEG.

Size guidelines

If you still need more help choosing the right image, check out our page on model and property releases.