Pesticide tank mixing requires precise calculations to apply the correct active ingredient rate while filling your spray tank efficiently. Too little under-protects your crop; too much wastes money and risks crop injury or environmental harm. This calculator handles the math for any tank size and application rate, with both imperial (gallons/oz) and metric (liters/mL) support.
Spray Parameters
From product label (use rate per acre or per hectare)
Typical: 10-20 gal/acre for herbicides, 15-25 for fungicides
Mix Results
How to Use the Pesticide Mix Calculator
Correct pesticide mixing ensures you apply the labeled rate every time — protecting your crop effectively while avoiding waste, crop injury, or environmental contamination. Always read the full product label before mixing; the label is the law.
Step 1: Find Your Application Rate on the Label
The product label specifies use rates in fl oz/acre, pts/acre, or lbs/acre (imperial) or L/ha or g/ha (metric). Use the rate for your target pest and crop. For pre-emergent herbicides, use the higher rate in the range; for in-season applications on sensitive crops, start at the lower rate.
Step 2: Determine Your Carrier Volume (GPA)
Gallons per acre (GPA) depends on your nozzle selection, sprayer speed, and pressure. A sprayer running 10 mph with TeeJet 11003 nozzles at 40 PSI spaced 20 inches apart will apply about 15 GPA. Calibrate your sprayer with clean water before the season. GPA × tank capacity = acres per tank.
Step 3: Handle the Last Partial Tank
The last tank problem is a common source of over-application. If your last tank only covers 18 acres but your tank covers 25 acres when full, mix only 18/25 × 72% of a full tank of water and product. Never run a full tank of product over fewer acres than intended. This calculator computes last-tank amounts automatically.
Safe Mixing Order
The standard safe mixing order: fill tank 1/4 with water → add wettable powders and dry flowables → add water-soluble packets → add surfactant → add emulsifiable concentrates → fill tank to desired level. Never mix concentrated products together before adding water. Keep agitator running throughout.
FAQ
Is this pesticide calculator free?
Yes, completely free. No signup or account needed. All calculations run in your browser.
How do I calculate how much pesticide to put in my spray tank?
Multiply the product use rate (oz/acre or L/ha) by the acres the tank covers. If using 12 oz/acre and your 500-gallon tank covers 25 acres at 20 GPA, you need 300 oz of product per tank. Always fill the tank partially with water, add product, then top off while mixing.
What is gallons per acre (GPA) for spraying?
GPA is the total spray volume applied per acre, determined by nozzle flow rate, speed, and spacing. Field sprayers typically run 10-20 GPA for herbicides. Fungicide and insecticide applications often use 15-25 GPA for better canopy penetration. Aerial applications run 1-5 GPA.
How do I convert oz/acre to mL/hectare?
Multiply oz/acre by 73.07 to get mL/ha. Alternatively: 1 fl oz/acre = 73.07 mL/ha. If the label says 12 fl oz/acre, that equals 877 mL/ha. This calculator handles both unit systems automatically.
What is the last tank problem and why does it matter?
The last tank problem occurs when you have fewer acres left than a full tank covers. You must mix a partial tank at the same concentration. Calculate partial tank volume by multiplying remaining acres × GPA, then scale the product amount proportionally. Never overapply to empty the tank.