Spray Rate Conversion Calculator
Based on the information you have available, choose Option A or Option B below.
Option A: Based on Rate per Hectare
Use this option if you know how much area your sprayer or knapsack covers.
It will calculate:
- How much herbicide to add to your sprayer (in mls), and
- The required spray concentration (ml of herbicide per 1L of water)
Option B: Based on Known Mix Rate
Use this option if you know the required per hectare rate (L/ha) and the herbicide concentration (ml/L) you plan to use.
It will calculate:
- How much area your sprayer must cover to match the correct rate, and
- The total amount of herbicide needed
Disclaimer: This calculator is provided as a general guide only. Rainbow & Brown accepts no responsibility for errors or outcomes resulting from its use. Users must verify all calculations and ensure application rates comply with product labels, local regulations and best agricultural practices.
Understanding Spray Volumes: Making Sense of Your Calculator Results
Now that you’ve used the calculator, here’s how to interpret the results and make sure you’re spraying the correct amount – regardless of your gear or how much water you use.
Boom Spraying
With boom spraying, different people may use different volumes of water per hectare depending on their equipment, speed, and perception of leaf wetness. That’s fine—as long as the correct amount of chemical is applied per hectare.
For example, one person might use 80L and another 120L of water per hectare. As long as both add the right amount of herbicide for one hectare (say, 2L), the results will be the same.
It’s the chemical rate per hectare that matters, not the water volume.
Handgun & Knapsack
If you're using a knapsack or handgun, it’s harder to know your spray area—because these tools are often used for spot spraying.
To use the calculator effectively, you first need to calibrate your gear. Do a quick test with plain water to figure out how much area you typically cover with, say, 5L or 15L. Once you know that, plug the numbers into Option A on the calculator.
Once you know your Numbers...
Once you’ve worked out how much area your sprayer covers, the calculator does the hard work for you. Just plug in your details and it’ll tell you exactly how much herbicide to add, and how strong your mix should be. It’s a quick one-time job that makes every spray from then on super easy.
