Choose a substitute based on your dish: drinks/marinades (lime or lemon) vs. cooked recipes (vinegar + citrus).
Start with the listed ratio; if your substitute is sharper (lemon, ACV), use slightly less and ramp up gradually.
For flavor closer to calamansi, add zest (mandarin/orange) after mixing, not before heating.
Adjust balance: add a small amount of sugar/honey for drinks or sauces that taste too thin or too tart.
In baking, reduce other acids slightly and let the batter rest 5 minutes so acidity “settles” before judging.