Copper Fungicide Dilution Calculator

About this calculator

Copper-based fungicides (such as copper hydroxide, copper sulfate, or Bordeaux mixture) are diluted in water before spraying, and getting the dilution right matters because too little copper fails to control disease while too much can scorch foliage or build up to phytotoxic levels in the soil. This calculator takes your water volume, the product's labeled dilution rate, and its copper content percentage, and works out both how much product to add and the resulting elemental copper concentration of the finished spray.

Home gardeners, orchardists, and vineyard managers use copper sprays to control fungal and bacterial diseases like peach leaf curl, early blight, downy mildew, and fire blight, typically applying them preventively before wet weather. Because copper products vary widely in strength and are labeled in different units (ounces per gallon, grams per liter, or percentage metallic copper equivalent), this calculator helps translate the label instructions into an exact mixing amount for your sprayer.