25 grams of ground coffee is a standard amount often used for brewing a single cup. It is about the size of a large egg.

In kitchen measures
4.23 tablespoons
12.7 tsp · 4.23 tbsp · 0.264 cups
about the size of a large egg
Ground coffee typically ranges 0.35–0.48 g/mL depending on how it's packed. A firmly packed scoop weighs more.