A chart to cross reference a button cell battery can be found on certain brand-name battery websites. A chart is needed as there are many different styles, sizes and types of button cell batteries.
Some websites have many different types of charts for different brands and sizes. You will need the brand and size of the battery; the chart will provide you with the battery number. In the brand number, LR means alkaline chemistry, the three-digit model name begins with a one, SR means silver oxide chemistry, the three-digit model name begins with a three. On the specific brand websites, there are chart conversions for those particular brands only.