Match your use: for glazing and stir-fries, pick the closest sweet-savory option (Peking duck sauce or teriyaki+bean paste).
Use the table ratio (1:1) as your starting point, then adjust thickness and sweetness to match your dish.
If your substitute is thinner than hoisin, simmer 1–2 minutes or whisk in a pinch of cornstarch slurry (1 teaspoon cornstarch + 1 tablespoon cold water).
If it’s too sweet, add 1–2 teaspoons soy sauce per cup; if too salty, add 1–2 teaspoons brown sugar per cup.
Taste once cooked (not raw) and aim for hoisin’s balance: sweet first, then savory depth, with a thick, glossy finish.