Calculate mixture ratio of concentrate and water for target concentration.
The pesticide dilution calculator splits a spray tank into exact amounts of concentrate and water, given three numbers: the active-ingredient concentration on the product label (%), the spray concentration you want (%), and the total volume to mix in gallons. It answers the question label math often leaves implicit — how many fluid ounces (and milliliters) of concentrate go into this particular tank — and works the same for insecticides, fungicides, and horticultural oils. The target concentration can never exceed the label concentration; dilution only goes downward. Always follow your product label's rates and safety directions.
Total volume in fluid ounces = gallons × 128. Concentrate needed = (target % ÷ label %) × total ounces — the standard C₁V₁ = C₂V₂ dilution identity solved for the concentrate volume. Water = total − concentrate. Both outputs are also converted to milliliters at 29.5735 ml per fluid ounce for metric measuring cups and syringes. The tool validates inputs: label concentration must be between 0 and 100%, and the target must be positive and no higher than the label strength.
Diluting a 50% concentrate to a 0.5% spray in a 2-gallon tank (256 oz) takes (0.5 ÷ 50) × 256 = 2.56 oz of product — about 75.7 ml — topped with 253.44 oz of water. Tiny doses like this are why a measuring syringe beats eyeballing.
A 25% concentrate mixed to 1% in 1 gallon needs (1 ÷ 25) × 128 = 5.12 oz (≈151 ml) of concentrate and 122.88 oz of water. The 1:25 target-to-label ratio drives everything.
An 80% product sprayed at 2% in a 5-gallon backpack (640 oz) requires 16 oz of concentrate — exactly one US pint, or 473.2 ml — plus 624 oz of water.
Dilution can only lower concentration — you would need more than 100% of the tank to be concentrate. The calculator rejects targets above the label percentage as physically impossible.
The tool already does: 1 US fluid ounce = 29.5735 ml. A 2.56 oz dose shows as 75.7 ml, convenient for the metric syringes and cups most concentrate kits include.
Convert it: ounces per gallon ÷ 128 × 100 gives the spray percentage. For example, 2.5 oz per gallon ≈ 1.95%. Use that as the target with the product's labeled active-ingredient percentage.
No — the C₁V₁ = C₂V₂ identity applies to any liquid concentrate. What changes is the appropriate target rate, which always comes from the specific product label, not from this tool.