Identify your use: topping/sandwich (need crunch), cooked sauce/pasta (need tang), or briny pickled side (need liquid bite).
Choose the closest match: pickled banana peppers or pepperoncini for mild tang, then adjust heat with seeds removed or a pinch of chili.
Use the listed ratio; if your jar is drier (less brine), add 1–2 teaspoons of brine/vinegar from the substitute jar to replace the missing tang.
Taste after adding: increase heat with a small pinch of chili flakes or reduce it by adding a touch of sugar or extra oil (if the recipe allows).
For dishes that need crunch, stir in right before serving instead of simmering long.