A common resolution used for a web graphic is:

The resolution of 72 pixels per inch (ppi) is widely recognized as a standard for web graphics. This choice is optimal because it strikes a balance between acceptable quality and file size, making images load efficiently on web pages. Historically, 72 ppi was established based on early monitors, which rendered images at this resolution. While other resolutions, such as 96 ppi, are also common and might provide slightly better quality on some displays, 72 ppi is still the traditional benchmark for most online applications. Consequently, using this resolution helps ensure that images appear sharp enough for web viewing while maintaining manageable file sizes for quick loading times.