Herbicide Calculator
Estimate treated acres, herbicide product amount, spray carrier, tank batches, active ingredient loading, adjuvant amount, and nozzle output for field, banded, and spot applications.
Use this planner after you have chosen a registered product and crop/site from the current label. It calculates quantities from label rates; it does not choose products, diagnose weeds, or authorize an application.
Herbicide Mix Results
Results use treated-area math. Before loading the sprayer, compare every value with the current label, your calibration catch test, and local application restrictions.
| Area or volume item | US value | Metric value | Formula use |
|---|---|---|---|
| 1 acre | 43,560 sq ft | 0.404686 ha | Base field area conversion |
| 1 hectare | 2.47105 ac | 10,000 m² | Metric field area conversion |
| 1 gallon | 128 fl oz | 3.78541 L | Liquid product and tank conversion |
| 1 pound | 16 oz dry | 0.453592 kg | Dry product and active ingredient conversion |
| Banded area | field ac x band/row | field ha x band/row | Use same width units for the ratio |
| Example herbicide family | Common label-rate style | Typical carrier volume | Active basis to enter | Critical label check |
|---|---|---|---|---|
| Glyphosate 4 lb ae/gal | 22 to 44 fl oz/ac on many labels | 5 to 20 GPA by application | 4 lb ae/gal | Crop/site, surfactant, water conditioning, drift |
| Glufosinate 2.34 lb ai/gal | 29 to 43 fl oz/ac on many labels | 15 to 20 GPA minimum on many labels | 2.34 lb ai/gal | Weed size, AMS, LibertyLink trait, time of day |
| 2,4-D amine or ester | 1 to 2 pt/ac for many field uses | 10 to 20 GPA common | 3.8 lb ae/gal often | Crop interval, volatility, nearby broadleaf crops |
| Atrazine 4L | 1 to 2 qt/ac by soil and crop limits | 10 to 30 GPA common | 4 lb ai/gal | Soil texture, groundwater rules, seasonal maximum |
| Clethodim 2E | 6 to 16 fl oz/ac common range | 10 to 20 GPA common | 2 lb ai/gal | COC/MSO requirement, grass size, crop interval |
| Metribuzin 75DF | 0.33 to 1 lb/ac by soil and crop | 10 to 20 GPA common | 75% by weight | Soil pH, variety sensitivity, rotational limits |
| Carrier and tank planning | Useful rule | Example | Why it matters |
|---|---|---|---|
| Finished spray volume | treated acres x GPA | 40 ac x 15 GPA = 600 gal | Sets total mix and water needs |
| Usable tank volume | tank size x fill limit | 500 gal x 90% = 450 gal | Leaves agitation and foam space |
| Acres per full tank | usable tank / GPA | 450 gal / 15 GPA = 30 ac | Sets product per load |
| Clean-water buffer | finished mix x buffer % | 600 gal x 5% = 30 gal | Helps plan rinse and unexpected overlap |
| Liquid product displacement | water approx = mix - product - adjuvant | Do not overfill before adding product | Prevents tank overflow and poor agitation |
| Nozzle and speed calibration | US formula | Metric formula | Field check |
|---|---|---|---|
| Nozzle flow | GPM = GPA x MPH x spacing in / 5940 | L/min = L/ha x km/h x spacing cm / 60000 | Catch each nozzle for one minute |
| 10 GPA, 6 mph, 20 in | 0.20 GPM/nozzle | 0.76 L/min | Often near an 02 nozzle output |
| 15 GPA, 6 mph, 20 in | 0.30 GPM/nozzle | 1.14 L/min | Common postemergence boom target |
| 20 GPA, 5 mph, 20 in | 0.34 GPM/nozzle | 1.26 L/min | Useful when coverage is the priority |
| 30 GPA, 4 mph, 20 in | 0.40 GPM/nozzle | 1.51 L/min | Heavy coverage or brush/spot-style work |
| Adjuvant or safety item | Common planning value | Calculator entry | Label and safety check |
|---|---|---|---|
| NIS surfactant | 0.25% v/v often listed | Type NIS, rate 0.25 | Only if allowed or required by label |
| COC or MSO | 0.5% to 1% v/v common | Type COC or MSO, rate 1 | Crop injury risk may increase |
| AMS water conditioner | 8.5 to 17 lb/100 gal common | Type AMS, rate 8.5 or 17 | Follow product and herbicide label order |
| Drift buffer | Use label-specific distance | Not a substitute for label | Wind, inversion, boom height, droplet size |
| PPE and REI | Signal words and label section | Not calculated | Wear required PPE; follow restricted-entry interval |
Before mixing: Calibrate with clean water at the same pressure, nozzle set, speed, boom height, and nozzle spacing you plan to use in the field. Replace tips that are outside the accepted wear range.
Before banding: Keep the rate basis clear. Apply the labeled rate to treated acres, then reduce total product by the band-to-row ratio only when the label allows that treated-area method.
Mixing your herbicide can be easy in theory but messier in practice. If you have a field size, label rate, a spray volume target, and a tank that won’t hold everything at once, suddenly math matter. How do you make those components work together and neither go over nor under the maximum level of active ingredient permitted on the label?
Before applying any product to the tank you need to know if you are treating the entire field or only certain bands. That will impact number of acres you treat and thus the volume of mix in the tank, as well as amount of refills. How many loads do you think you can safely make with a tank? Safe fill limits and size of your tank answers that question.
How to Mix Your Sprayer Correctly
The math isn’t complex, but it multiplies fast on big fields and when using small measurements like ounces. For that reason, it’s also important to pay attention to active ingredient calculations; not all products is formulated at equal rates (e.g., some has more material in each gallon than others). And if there’s an upper limit on amount used per application or season, as some labels do, you can convert the label rate to pounds of active ingredient per acre and see if you’re within that limit. It will also tell you if a given product is a liquid or a powder, which may be simpler to measure out for task at hand.
Gallons per minute: Knowing this number tells you whether your current tips are working, whether pressure and speed need adjustment, and when you should of replace a worn nozzle that’s not putting out an even spray. The math of nozzles adds up fast, considering the gallons per minute that each tip has to put out, taking into account your travel speed and nozzle spacing.
The same applies to adjuvants, because the calculator will show how much conditioner or surfactant to add based off what you are using and its percentage concentration. That amount displace water, so order of addition and final fill level both matter for keeping the tank from overflowing or leaving product poorly suspended. So if you want to avoid spilling your tanks over, make sure you think about when each item is added. Is it being shaken up enough? Does the final fill level allow the product stays suspended well enough?
For example, using total tank size instead of usable volume will change number of batches needed and product per load. Counting each acre on the map as a treated acre will also change those numbers. Entering the band width ratio backwards will produce same result. Counting spot applications as full coverage will also produce the same result. These are common mistakes.
Bottom line: Run the number as a matter of practice after you’ve selected the label/product combination; compare that result with both the calibration sheet and limits. It’s simple math, provided you know what goes into the equation, and something that needs to be done with actual label in-hand (not from memory).
