Skip to main content
What Grass Is This? LogoWhat Grass Is This?
Seasonal tool

Tank Mix Calculator

Calculate exactly how much herbicide and surfactant to mix per gallon of water. Spot and blanket rates for Tenacity, quinclorac, 2,4-D, and more, with step-by-step mixing order.

Tool inputs

1 minute
Location
Grass type
Lawn details
Beat weeds and brown spots with the free iPhone app
Download on the App Store

Tank mixing, done right

How to read a herbicide label rate

Labels give rates per acre or per 1,000 sq ft. Homeowners spray by the gallon. Converting between the two is where most mixing mistakes happen.

Does your label give a rate per gallon of water or per treated area? The store presets use the label's concentrate amount plus measured water. A batch made with 1 gallon of water exceeds 1 gallon after concentrate is added. Choose a permitted sprayer with enough capacity and stay below its fill limit. Follow the selected label row's coverage.

Pro blanket recipes convert an area rate using an assumed 1 gallon of finished spray per 1,000 sq ft. Calibrate the sprayer with water to confirm that coverage before mixing. Pro spot recipes use measured water and the label's spot directions. Spot treatment still has area and annual limits. For liquid measures, 1 US fl oz equals 6 teaspoons; dry products use the displayed level teaspoons.

The GroundClear Year Long manufacturer directions specify 24 fl oz plus 1 gallon of water for up to 300 sq ft. The products and all that water must fit below the sprayer's fill limit.

The Syngenta Tenacity spot-treatment directions specify 1 teaspoon in 2 gallons of water with 3 teaspoons of non-ionic surfactant. Follow the product label's coverage and application limits.

The label is the law. Rates in this tool are common homeowner starting points from public labels, but your product's label always wins, because formulations and concentrations vary between brands.

Surfactants: the ingredient people skip

Most post-emergent herbicides need a surfactant to stick to and penetrate the waxy leaf surface. Skipping it is the number one reason a spray "didn't work."

  • Non-ionic surfactant (NIS): the default. About 1 to 2 tsp per gallon. Pairs with Tenacity, 2,4-D, triclopyr, and Celsius.
  • Methylated seed oil (MSO): stronger penetration for tough grassy weeds. About 0.55 fl oz (3.3 tsp) per gallon. The label choice for quinclorac on mature crabgrass.
  • None needed: consumer glyphosate concentrates already include surfactant in the jug.
  • Dish soap is not a substitute. It foams, degrades some actives, and isn't consistent enough to dose.

Sprayer setup and cleanup

The right mix in a dirty or badly calibrated sprayer still burns lawns.

Check the product label for permitted sprayers, protective equipment and mixing directions. A stated water volume does not mean a sprayer of that capacity can hold the whole batch.

After use, follow the product label and sprayer manufacturer's cleaning directions. Use a cleaning agent only when those directions specify it. Follow the label's rinse-water disposal instructions. Keep pesticide and rinse water out of drains and surface water.

Rate tells you how much; timing tells you when. Pair this tool with the Herbicide Timing Calculator so you're spraying when the weed is actually vulnerable.

Frequently asked questions

Does 1 gallon mean water or finished spray?

Store presets use a measured gallon of water plus the listed concentrate. For example, GroundClear Year Long uses 24 fl oz plus 1 gallon of water. The finished batch exceeds 1 gallon, so use a label-permitted sprayer with enough capacity. Stay below its fill limit. Pro spot recipes also use measured water. Pro blanket recipes use a gallon of finished spray per 1,000 sq ft; add water to reach that final volume. Check your exact bottle label before mixing.

How much Tenacity do I mix per gallon of water?

For spot spraying, mix half a teaspoon (about 0.08 fl oz) of Tenacity per gallon of water plus 1.5 teaspoons of non-ionic surfactant, and spray it at about 1 gallon per 1,000 sq ft. A blanket broadcast is a separate label rate: 4 to 8 fl oz per acre, about 0.09 to 0.18 fl oz (0.55 to 1.1 teaspoons) per 1,000 sq ft. The calculator uses the low end. Always confirm against your label before spraying.

How much Spectracide Weed Stop do I mix per gallon of water?

Spectracide Weed Stop For Lawns Concentrate2 changes by grass: 2 fl oz (4 Tbsp) per gallon of water on bluegrass, fescue, ryegrass, and zoysia, 1 fl oz (2 Tbsp) on Bermuda, bahia, bentgrass, and centipede, and 0.75 fl oz (1.5 Tbsp) on St. Augustine. Each batch made with 1 gallon of water treats 500 sq ft. Plus Crabgrass Killer uses 5 fl oz per gallon of water for spot spraying (500 sq ft) or 6.4 fl oz per gallon of water for a whole lawn (1,000 sq ft). It is not for St. Augustine, centipede, bahia, or bentgrass. Check the exact bottle and grass exclusions before mixing.

What is the Ortho WeedClear concentrate mix ratio?

WeedClear Lawn Weed Killer Concentrate (the North bottle that kills crabgrass) mixes at 2.5 fl oz (5 Tbsp) per gallon of water for every 400 sq ft, on bluegrass, ryegrass, fescue, Bermuda, zoysia, and buffalograss only. WeedClear Weed Killer for Lawns Concentrate uses 2 fl oz per gallon of water on northern grasses and 1 fl oz per gallon of water on southern grasses. Each batch made with 1 gallon of water treats 500 sq ft. Follow your bottle's grass and cultivar exclusions.

How much Roundup concentrate do I mix per gallon?

Roundup Weed & Grass Killer Concentrate takes 6 fl oz (12 Tbsp) per gallon of water, or 3 fl oz for newly emerged annual weeds under 3 inches. Roundup Super Concentrate uses 1.5 fl oz (3 Tbsp) per gallon of water for annual weeds and 2.5 fl oz (5 Tbsp) for tough ones. Each batch made with 1 gallon of water treats 300 sq ft. Both kill lawn grass. Use only on sites listed on the bottle, and keep spray off plants you want to keep.

What is the Ortho GroundClear concentrate mix ratio?

GroundClear Super takes 5 fl oz per gallon of water for most weeds and 10 fl oz for established ones. Each batch made with 1 gallon of water treats 350 sq ft. GroundClear Year Long takes 24 fl oz (3 cups) per gallon of water for up to 300 sq ft. The finished batch exceeds 1 gallon. Year Long stays in the soil for up to a year. Never use it near a lawn, tree roots, or anywhere you plan to plant.

How much surfactant do I add per gallon?

Non-ionic surfactant (NIS) is typically 1 to 2 teaspoons per gallon of finished mix (about 0.25 fl oz). Methylated seed oil (MSO) runs stronger at about 3.3 teaspoons (0.55 fl oz) per gallon. Use the surfactant your herbicide label calls for: quinclorac works best with MSO, while Tenacity and most broadleaf herbicides pair with NIS.

What order do I mix herbicide and surfactant in the tank?

Follow your product label's mixing order. For these store presets, measure half the required water into a permitted sprayer, add the concentrate and agitate, then add the remaining measured water. Do not add surfactant to store presets. Pro recipes add the listed surfactant only when the label calls for it. A water-based recipe needs all the measured water plus the products; a pro blanket recipe needs water added to the stated finished spray volume. Use a sprayer with enough capacity and stay below its fill limit.

Why are spot spray rates different from blanket rates?

Spot and blanket directions can use different product amounts and coverage rules. Follow the selected label row. The pro blanket calculation assumes 1 gallon of finished spray per 1,000 sq ft. Tenacity's spot recipe uses half a teaspoon per gallon of water and requires application at about 1 gallon per 1,000 sq ft. Store presets use their own label coverage, shown with each recipe. A spot recipe does not remove the label's area or annual limits.

Can I mix two herbicides in the same tank?

Often yes, but only when both labels allow it. Do a jar test first: mix small amounts in a jar of water and watch for clumping or separation. Common safe combos include quinclorac plus a three-way broadleaf herbicide for crabgrass and broadleaf weeds in one pass. Never tank-mix products whose labels prohibit it.

How long is mixed herbicide good for in the tank?

Plan to spray the same day you mix. Most herbicides begin degrading in water within 24 hours, and some (like sulfonylureas) break down faster in acidic or warm water. Mix only what you'll use, and triple-rinse the sprayer afterward.

Related articles

Pre-Emergent Timing: When to Apply by ZIP CodeScotts Weed and Feed Application GuidePre-Emergent Herbicide Timing Guide