The SCA recommends a golden ratio of 1:18 (1g coffee to 18ml water). However, different methods have their own sweet spots: pour over is typically 1:16, French press 1:15, and espresso 1:2.
For stronger coffee, use less water (e.g., 1:14). For milder coffee, use more water (e.g., 1:18). Finer grinds also increase extraction for a bolder taste.
A standard 240ml cup of pour over coffee uses about 15g of ground coffee. Two cups need about 30g. Adjust to your taste preference.