When hojicha is part of the day, its caffeine content may be something you want to understand. Japanese public information gives a value together with the method used to brew the tea. The conditions are part of the figure.
The figure and the infusion
The Ministry of Agriculture, Forestry and Fisheries lists hojicha infusion at 0.02 g per 100 mL, or 20 mg per 100 mL. The stated method uses 15 g of tea, 650 mL of water at 90°C, and 0.5 minutes.
The tea figures in this table come from the Standard Tables of Food Composition in Japan 2020 (eighth revised edition). They describe the infusion prepared under those conditions.
Differences in brewing, differences between people
The Food Safety Commission of Japan explains that caffeine content varies with the type and quantity of ingredients and the extraction method. Changing the amount of tea, water volume, temperature or brewing time can change the value. A bottled drink or a pot brewed at home will not necessarily match the composition table.
The commission also explains that sensitivity to caffeine differs greatly between individuals. This makes its health effects difficult to assess accurately, and no acceptable daily intake (ADI) has been set internationally. The same publication introduces intake guidance from overseas bodies; those guidance figures are distinct from an ADI.
Choosing how much to drink
The published value alone cannot establish a number of cups that is suitable for everyone.
If you are pregnant, choosing a drink for a child, or concerned about your own sensitivity to caffeine, please consult official guidance, such as that from the Food Safety Commission of Japan.