Herbicide Rate Calculator and Pesticide Mix Calculator
Use this spray tank mix calculator to answer common label-rate questions: product per gallon, product per tank, product per acre, product per 1,000 sq ft, and total product for a field, lawn, garden, backpack sprayer, or broadcast rig.
Before You Mix
Follow the product label first. Confirm the product is registered for your crop, site, pest, and location; wear required PPE; observe re-entry and pre-harvest intervals; avoid incompatible tank mixes; and calibrate the sprayer before applying. This calculator supports mixing math, not label approval or agronomic advice.
Spray Mix Inputs
1. Read the label rate
Example: 22 for 22 fl oz/acre, or 2 for 2 fl oz per 1,000 sq ft.
Use the format printed on the product label. Dry product units return dry-weight outputs.
2. Enter carrier volume and tank size
Example: 15 GPA. This should come from sprayer calibration.
Use the actual fill volume. Backpack examples: 1, 2, or 4 gallons.
3. Enter treated area and application pattern
Example: 120 acres, 0.25 acre, or 10,000 sq ft.
Banded spraying reduces treated area by band width divided by row spacing.
Optional sprayer calibration helper
Estimate GPA from nozzle output, boom or swath output, or water sprayed over a measured test area.
Gallons per minute from one nozzle.
Gallons per minute from the whole boom or wand setup.
Miles per hour for nozzle and swath methods.
Mixing Summary
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How to Use the Calculator
- Read the product label and enter the product rate exactly as written.
- Enter your calibrated carrier volume, such as 15 GPA or 140 L/ha.
- Enter the tank size or choose a common 1, 2, 4, 15, 25, or 100 gallon tank.
- Enter the total area and choose broadcast or banded application.
- Calculate, then verify label directions, calibration, PPE, intervals, and tank-mix compatibility before measuring product.
Formula Guide
Carrier volume converts the label rate into a tank mix. For a broadcast application, tank coverage = tank volume ÷ carrier volume per acre or hectare.
Product per gallon = label rate per acre ÷ GPA. Product per liter = label rate per hectare ÷ L/ha. Product per full tank = product per gallon or liter × tank volume.
Total product = product rate × treated area. For banded spraying, treated area = field area × band width ÷ row spacing.
Number of full tanks = floor(total carrier volume ÷ tank volume). Final partial tank volume = remaining carrier volume. Product for the partial tank = product per gallon or liter × final partial volume.
Useful conversions: 1 gallon = 128 fl oz = 3.785 L; 1 pint = 16 fl oz; 1 quart = 32 fl oz; 1 acre = 43,560 sq ft; 1 hectare = 2.471 acres; 1 tablespoon = 3 teaspoons.
Worked Examples
Field sprayer
Input 22 fl oz/acre, 15 GPA, and a 400-gallon tank. Product per gallon = 22 ÷ 15 = 1.47 fl oz/gal. Tank coverage = 400 ÷ 15 = 26.7 acres. Product per tank = 22 × 26.7 = 586.7 fl oz, or about 4.58 gallons.
Backpack sprayer
If a label or local recommendation works out to 1.47 fl oz/gal, a 1-gallon hand sprayer takes 1.47 fl oz and a 4-gallon backpack takes 5.87 fl oz. Use the tank shortcuts to recalculate for 2-gallon and 4-gallon tanks.
Lawn application
For 2 fl oz per 1,000 sq ft over 10,000 sq ft, total product = 2 × 10 = 20 fl oz. If your calibrated sprayer applies 1 gallon per 1,000 sq ft, a 4-gallon tank covers 4,000 sq ft and needs 8 fl oz per tank.
Metric hectare
At 1.5 L/ha and 140 L/ha carrier volume, product per liter = 1.5 ÷ 140 = 10.7 mL/L. A 200 L tank needs about 2.14 L of product and covers 1.43 ha.
Partial final tank
With a 25-gallon tank, 15 GPA, and a 10-acre job, total water is 150 gallons. That is six full 25-gallon loads. If the job were 10.5 acres, total water would be 157.5 gallons: six full loads plus a 7.5-gallon partial load mixed at the same product-per-gallon rate.
FAQs
How do I calculate herbicide per gallon?
Divide the label rate per acre by your calibrated GPA. For example, 22 fl oz/acre at 15 GPA equals 1.47 fl oz per gallon. If the label already gives teaspoons, tablespoons, percent solution, or product per gallon, choose that rate unit directly.
How much product goes in a 25-gallon sprayer?
Calculate product per gallon, then multiply by 25. At 1.47 fl oz/gal, a 25-gallon sprayer needs about 36.7 fl oz.
What if the label rate is per acre but I am spraying square feet?
Convert the site area to acres or use the square-foot area unit. One acre equals 43,560 square feet, so 10,000 sq ft is 0.2296 acre.
How do I mix a partial tank?
Use the same product-per-gallon or product-per-liter rate as a full tank, then multiply by the final partial water volume. The calculator reports the final partial tank volume and product amount.
What is GPA?
GPA means gallons of carrier volume applied per acre. It is a sprayer calibration value, not a product rate.
Can I use this for dry products?
Yes. Choose dry oz/acre, lb/acre, grams/hectare, or lb/1,000 sq ft. The calculator returns dry-weight amounts instead of fluid ounces.
What is the difference between product rate and active ingredient rate?
Product rate is the amount of formulated product from the label. Active ingredient rate is the amount of active chemical inside that product. This calculator uses product rate unless a label explicitly tells you to convert active ingredient to product first.
Why must I calibrate my sprayer first?
The same label rate can produce different tank mixes at 10 GPA, 15 GPA, or 30 GPA. Calibration tells you how much water your sprayer applies so the product concentration per gallon is correct.
Practical Mixing Guidance
Read the label rate basis
Check whether the label rate is per acre, per 1,000 sq ft, per gallon, percent solution, or per tank. Do not mix active ingredient rates with product rates unless the label gives the conversion.
Carrier volume changes concentration
A lower GPA means more product per gallon for the same per-acre rate. A higher GPA means a more dilute tank mix, but the same total product per acre.
Tank size changes coverage
A larger tank usually reduces the number of fills. It does not change the labeled product rate; it changes how much water and product go into each load.
Avoid common conversion mistakes
Keep dry ounces separate from fluid ounces, confirm whether "oz" on the label means fluid or dry product, convert square feet to acres when needed, and mix partial tanks with the same concentration as full tanks.
Safety Reminder
Use these results only as a mixing-math check. Follow the product label, EPA or local registration, PPE directions, re-entry intervals, pre-harvest intervals, weather limits, buffer requirements, and tank-mix compatibility instructions.