About the Sprayer Mix Calculator
This sprayer mix calculator converts the application rate printed on a herbicide, insecticide, fungicide or liquid fertilizer label into the amount of concentrate to pour into your tank. Labels state rates in three common ways — fluid ounces per 1,000 square feet, fluid ounces per acre, or fluid ounces per gallon of water — and this tool handles all three.
It is built for homeowners with a 1–4 gallon pump sprayer, lawn-care operators with backpack or skid sprayers, and small-acreage owners pulling a 25–100 gallon boom or spot sprayer. Enter your tank size and how much spray your sprayer puts out over a given area (its calibrated carrier volume) and you get ounces per gallon, ounces, milliliters and tablespoons per tank, the area each tank covers, and the total product and water for the job.
The result is only as good as your calibration: spray a measured area with plain water first to learn how many gallons you actually apply per 1,000 sq ft or per acre. Always follow the product label — it is the legal limit for rate, mixing order, protective equipment and re-entry time.
With the default inputs, the concentrate per full tank is 3 fl oz. Change any value above to recalculate instantly.
How to use the sprayer mix calculator
- 1Choose how the label states its rate and enter the rate for your target.
- 2Calibrate your sprayer with water and enter the gallons it applies per 1,000 sq ft or per acre.
- 3Enter your tank size in gallons.
- 4Enter the area you need to treat.
- 5Add the concentrate per tank shown, then top up with water following the label mixing order.
Formula and method
When the label gives a rate per area (per 1,000 sq ft or per acre), the concentrate per gallon is the label rate divided by the gallons of spray your sprayer applies over that same area. Multiplying by the tank size gives the amount to add to a full tank, and dividing the tank size by the carrier volume tells you how much ground one tank covers. When the label gives a rate per gallon of water, that number is used directly and the carrier volume only sets the coverage.
Totals for the job use the area to treat: total spray = carrier volume × area, and total concentrate = ounces per gallon × total spray. One US fluid ounce is 29.57 mL and two tablespoons. The calculation assumes the label rate is for the concentrate as sold and that your sprayer has been calibrated with water.
- Rate
- Label rate in fl oz per 1,000 sq ft, per acre or per gallon
- Carrier volume
- Gallons of spray applied per 1,000 sq ft or per acre (from calibration)
- Tank
- Sprayer tank capacity in gallons
Worked examples
1.5 fl oz per 1,000 sq ft in a 2-gallon pump sprayer
Spraying 1 gallon per 1,000 sq ft means each gallon must carry the full 1.5 fl oz. A 2-gallon tank therefore gets 3 fl oz (6 tbsp, about 89 mL) and covers 2,000 sq ft. A 5,000 sq ft lawn takes 2.5 tank loads, 5 gallons of mix and 7.5 fl oz of concentrate.
32 fl oz per acre in a 25-gallon spot sprayer at 20 GPA
At 20 gallons per acre, each gallon must hold 32 ÷ 20 = 1.6 fl oz, so a 25-gallon tank gets 40 fl oz and covers 1.25 acres. Three acres need 60 gallons of mix (2.4 tanks) and 96 fl oz of product.
2.5 fl oz per gallon in a 4-gallon backpack sprayer
The label says 2.5 fl oz per gallon, so a 4-gallon tank takes 10 fl oz (about 296 mL). Spraying 1 gallon per 1,000 sq ft, each tank covers 4,000 sq ft, and 10,000 sq ft needs 10 gallons of mix containing 25 fl oz of concentrate.
Frequently asked questions
How do I calibrate a pump sprayer?+
Mark out 1,000 sq ft (for example 20 × 50 ft), fill the sprayer with a measured amount of water and spray the area at your normal walking speed and pressure. Measure how much water is left; the amount used is your gallons per 1,000 sq ft.
How many ounces of herbicide per gallon of water?+
It depends entirely on the product and target. Divide the label rate per area by the gallons of spray you apply over that area: a 1.5 fl oz per 1,000 sq ft rate sprayed at 1 gallon per 1,000 sq ft is 1.5 fl oz per gallon; sprayed at 0.5 gallon it is 3 fl oz per gallon.
How many tablespoons are in a fluid ounce?+
One US fluid ounce equals 2 tablespoons, 6 teaspoons or about 29.6 milliliters. Measure concentrate with a dedicated measuring cup or syringe, never kitchen utensils used for food.
What if my sprayer applies more water than the label assumes?+
Applying more water per area dilutes each gallon but not the dose per area, as long as you scale the concentrate to your own carrier volume. That is why this calculator asks for your calibrated spray volume rather than assuming one.
Can I store leftover spray mix?+
Most labels advise mixing only what you will use that day, because many products break down or settle once diluted. Calculate the tank loads you need and part-fill the last tank so little or no mix is left over.