Roundup Ratio Calculator

Roundup Mixing Ratio Calculator

Calculate the exact herbicide concentrate needed for your sprayer.

US Units (Gallons/Ounces) Metric (Liters/Milliliters)

Mixing Instructions:

Herbicide Concentrate:
Water to Add:
Total Solution:

How to Use the Roundup Ratio Calculator

Using the correct herbicide ratio is critical for effective weed control and environmental safety. This calculator helps you determine the exact amount of Roundup concentrate (glyphosate) required to create a specific solution strength.

Understanding Solution Strengths

Different weed control tasks require different concentrations. Here are the common industry standards for mixing Roundup:

  • 0.5% Solution: Used for small annual weeds and general maintenance.
  • 1.0% to 1.5% Solution: The standard rate for most lawn weeds and grasses.
  • 2.0% Solution: Ideal for tough perennial weeds, brush, and woody vines.
  • Over 2.0%: Specific spot treatments or stump applications as directed by the product label.

The Mixing Formula

The math behind herbicide mixing is based on volume-to-volume ratios. To find the concentrate needed, we use the following logic:

Concentrate = Total Desired Volume × (Target Percentage / 100)

For example, to make 1 gallon of a 2% solution, you would need 0.02 gallons of concentrate. To make this practical, the calculator converts this into fluid ounces (2.56 fl. oz per gallon).

Safe Mixing Tips

  • Add Water First: Fill your sprayer with half of the required water before adding the concentrate to prevent excessive foaming.
  • Always Read the Label: Roundup products come in different concentrations (e.g., 18%, 41%, or 50% glyphosate). This calculator determines the volume of the product as it exists in your bottle.
  • Personal Protective Equipment: Wear gloves, long sleeves, and eye protection when handling concentrated herbicides.
function updateUnits() { var unit = document.getElementById("unitType").value; var label = document.getElementById("volumeLabel"); if (unit === "us") { label.innerText = "Total Spray Volume (Gallons)"; } else { label.innerText = "Total Spray Volume (Liters)"; } } function calculateRoundup() { var unit = document.getElementById("unitType").value; var targetPercent = parseFloat(document.getElementById("targetPercent").value); var totalVolume = parseFloat(document.getElementById("totalVolume").value); var resultDiv = document.getElementById("roundupResult"); if (isNaN(targetPercent) || isNaN(totalVolume) || targetPercent <= 0 || totalVolume <= 0) { alert("Please enter valid positive numbers for both concentration and volume."); return; } var ratio = targetPercent / 100; var concentrateVolume = totalVolume * ratio; var waterNeeded = totalVolume – concentrateVolume; var concentrateDisplay = ""; var waterDisplay = ""; var totalDisplay = ""; if (unit === "us") { // Convert concentrate to fluid ounces (1 gallon = 128 fl oz) var concentrateOz = (concentrateVolume * 128).toFixed(2); concentrateDisplay = concentrateOz + " fl. oz."; if (waterNeeded < 1) { waterDisplay = (waterNeeded * 128).toFixed(1) + " fl. oz."; } else { waterDisplay = waterNeeded.toFixed(2) + " Gallons"; } totalDisplay = totalVolume.toFixed(2) + " Gallons"; } else { // Convert concentrate to milliliters (1 liter = 1000 ml) var concentrateMl = (concentrateVolume * 1000).toFixed(1); concentrateDisplay = concentrateMl + " ml"; if (waterNeeded < 1) { waterDisplay = (waterNeeded * 1000).toFixed(0) + " ml"; } else { waterDisplay = waterNeeded.toFixed(2) + " Liters"; } totalDisplay = totalVolume.toFixed(2) + " Liters"; } document.getElementById("concentrateAmount").innerText = concentrateDisplay; document.getElementById("waterAmount").innerText = waterDisplay; document.getElementById("totalFinal").innerText = totalDisplay; resultDiv.style.display = "block"; }

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