Decide what mint role you need: cooling (cocktails/dressings), brightness (fruit/tea), or herb lift (savory sauces).
Choose the closest match from the list using the ratio, then chop or crush the substitute to release oils.
Add about 70% at first, mix well, and taste—mint flavor is easy to overshoot.
If your swap lacks the “cool” effect, compensate with a small squeeze of citrus or a tiny pinch of sugar (depending on the recipe).
Finish with the substitute late (if possible) to preserve freshness, especially for garnishes and uncooked drinks.