41% Glyphosate Mix Rate Calculator
Convert a 41% glyphosate label rate into product per full tank, acres per tank and the number of tanks a job needs. Every output shows the formula, the substituted numbers and the result, so the arithmetic can be checked against the product label. Rates and the per-100-gallon basis are US gallons.
Conversion and arithmetic only — always follow the product label.
Use the rate printed on the product label. This page converts units and does the arithmetic only.
UK gallons are converted to US gallons before any arithmetic: 1 UK gal = 1.20095 US gal.
Carrier volume source
Optional. GPA = 5,940 × GPM ÷ (mph × nozzle spacing in). If a calibration field is empty or not greater than zero, the entered GPA is used and a note explains it.
Enter a label rate, carrier volume, tank size and treatment area to see the tank mix and the step-by-step substitution.
How the calculation works
Every output is arithmetic on four entered values: the label rate, the carrier volume, the tank size and the treatment area. The calculator converts the rate to US fluid ounces first, then applies it per acre or per 100 US gallons, matching the label basis.
- Rate to fluid ounces: fl oz = rate × unit factor (1 for fl oz, 16 for pt, 32 for qt, 128 for US gal, 128 ÷ 9.756 for pounds of 41% SL product).
- Acres per full tank: acres per tank = tank volume in US gallons ÷ carrier volume in US gallons per acre (GPA).
- Product per full tank, per-acre basis: fl oz per tank = rate per acre in fl oz × acres per tank.
- Product per full tank, per-100-gallon basis: fl oz per tank = rate per 100 US gal × tank volume ÷ 100.
- Tanks needed: tanks = treatment area in acres ÷ acres per tank, rounded up to whole tanks. When the area is not an exact multiple, the last tank is partial: last tank mix = total mix − (whole tanks − 1) × tank volume.
- Total job: total mix = area in acres × carrier volume; total product = rate per acre × area, or rate per 100 US gal × total mix ÷ 100.
- Mix strength: % v/v = product volume in the tank ÷ tank volume × 100.
- Sprayer calibration: GPA = 5,940 × GPM ÷ (mph × nozzle spacing in), where 5,940 = 43,560 × 12 ÷ 88.
Worked label examples
Three worked examples built from real 41% glyphosate product labels. Each heading names the product; the EPA registration number, label revision date and source link are listed under Sources and label versions. The arithmetic follows the same steps as the calculator.
Example 1 — Hi-Yield KILLZALL II 41%: 2 quarts per acre
Rate: 2 qt × 32 fl oz/qt = 64 fl oz per acre (label range 1–2 qt/acre; this example uses the upper rate); carrier 15 US gal/acre (label window 10–40 GPA ground broadcast). Acres per full tank: 150 US gal ÷ 15 GPA = 10 acres per tank. Product per full tank: 64 fl oz/acre × 10 acres = 640 fl oz (5 US gal). Tanks: 25 acres ÷ 10 acres/tank = 2.5 tanks → mix 3. The last tank is partial: total mix 25 × 15 = 375 US gal, so the last tank is 375 − 2 × 150 = 75 US gal of mix with 64 × (75 ÷ 15) = 320 fl oz of product. Total mix: 375 US gal. Total product: 64 fl oz/acre × 25 acres = 1,600 fl oz (12.5 US gal). Mix strength: 5 gal ÷ 150 gal × 100 = 3.333% v/v ≈ 1 part product to 29 parts water.
Example 2 — Nufarm Credit 41 Extra: 2 gal per 100 gal (2%)
Rate: 2 US gal per 100 US gal = 256 fl oz per 100 gal (the label mixing table gives 2% = 2 gallons per 100 gallons). Acres per full tank: 100 US gal ÷ 20 GPA = 5 acres per tank. Product per full tank: 256 fl oz/100 gal × 100 gal ÷ 100 = 256 fl oz (2 US gal). Tanks: 5 acres ÷ 5 acres/tank = 1 tank exactly, so there is no partial tank. Total mix: 5 acres × 20 GPA = 100 US gal. Total product: 256 fl oz/100 gal × 100 gal ÷ 100 = 256 fl oz (2 US gal). Mix strength: 2 gal ÷ 100 gal × 100 = 2% v/v ≈ 1 part product to 49 parts water.
Example 3 — Compare-N-Save 41% Glyphosate: 2.5 fl oz per gallon
Rate: 2.5 fl oz per 1 US gal of water = 250 fl oz per 100 US gal. Area: 300 sq ft ÷ 43,560 = 0.006887 acres. Carrier volume: 1 gal of spray per 300 sq ft = 43,560 ÷ 300 = 145.2 US gal/acre. Acres per full tank: 1 US gal ÷ 145.2 GPA = 0.006887 acres per tank. Product per tank: 250 fl oz/100 gal × 1 gal ÷ 100 = 2.5 fl oz, which matches the label's 2.5 fl oz in 1 gallon of water. Tanks: 0.006887 acres ÷ 0.006887 acres/tank = 1 tank exactly, so there is no partial tank. Total mix: 0.006887 × 145.2 = 1 US gal. Total product: 2.5 fl oz. Mix strength: 2.5 fl oz ÷ 128 fl oz = 1.953% v/v ≈ 1 part product to 50.2 parts water.
Common ratio comparison
2% v/v and 50:1 are reference dilutions, not label rates. 2% v/v is 1 part product to 49 parts water; 50:1 is 1 part product to 50 parts water (about 1.96% v/v in the finished mix).
| Reference | fl oz per US gal | fl oz per 100 US gal | Mix strength |
|---|---|---|---|
| 2% v/v | 2.56 | 256 | 2% v/v |
| 50:1 | 2.56 | 256 | 1.96% v/v |
The calculator's Mix strength row puts the tank's own % v/v and water-parts ratio next to the 2% v/v and 50:1 references. For comparison, Example 1 (2 qt per acre at 15 GPA) works out to 3.333% v/v, so the reference dilutions do not replace the label rate.
Unit notes
- Tank size can be entered in US or UK gallons. 1 UK gallon = 1.20095 US gallons; a UK tank size is converted to US gallons before any arithmetic.
- Rates and the per-100-gallon basis are US gallons. 1 US gallon = 128 US fluid ounces; 1 qt = 32 fl oz; 1 pt = 16 fl oz. A per-100-gallon rate is applied to the finished spray volume; if the label says "per 100 gallons of water", the amount differs by the product-volume fraction (under 2% at typical dilutions).
- A pounds-per-acre rate is converted with 9.756 lb per US gallon of formulated product (4 lb a.i. per US gal ÷ 0.41 a.i. by weight). Confirm whether the label states pounds of product or pounds of acid equivalent.
- Area: 1 acre = 43,560 square feet. Square feet ÷ 43,560 = acres.
- Sprayer calibration: GPA = 5,940 × GPM ÷ (mph × nozzle spacing in inches). To hold a target GPA, speed = 5,940 × GPM ÷ (target GPA × nozzle spacing).
- Displayed values are rounded for readability; tanks are rounded up to whole tanks and the final tank may be a partial mix.
Input limits and errors
The calculator does not show a result while a required numeric field is empty, zero, negative or not a number. Each message names the field that needs attention.
- Label rate, carrier volume, tank size and treatment area must all be greater than zero.
- Calibration fields are optional. If nozzle flow, ground speed or nozzle spacing is empty or not greater than zero, the entered carrier volume is used and a note explains why.
- Values outside typical sprayer ranges still calculate but carry a note: carrier volume outside 1–500 GPA, tank outside 1–3,000 US gal, treatment area above 10,000 acres, per-acre rate outside 4–1,024 fl oz, per-100-gallon rate outside 0.5–1,024 fl oz.
- A dose equal to or larger than the tank volume, a dose below 0.01 fl oz, a partial last tank and mixing US and UK gallons are reported as notes, not as blocking errors.
- The calculation is rounded only for display and never shows an invalid number. If an input pair produces an out-of-range result, the calculator asks for a units check instead of showing a number.
- This page converts units and does arithmetic only. It does not choose a rate and does not replace the product label or local regulations.
Sources and label versions
Label citations, EPA registration numbers and revision dates for the three worked examples, plus the source for the 5,940 calibration constant. Always check the label supplied with the product, including state or local restrictions.
- Hi-Yield Super Concentrate KILLZALL II label (EPA Reg. No. 7401-467) — Source for the Example 1 rate: 1–2 quarts per acre applied in 10–40 gallons of spray solution per acre for ground broadcast. The example uses the upper 2 qt/acre rate at 15 GPA.No revision date printed on the label; EPA PPLS label copy file-dated 2005-07-18
- Nufarm Credit 41 Extra label (EPA Reg. No. 71368-20) — Source for the Example 2 per-100-gallon mixing rate and for the 41.0% / 4 lb a.i. per US gal data used to derive 9.756 lb product per US gal.No revision date printed on label; artwork footer dated 2/23/18
- Compare-N-Save Concentrate Weed & Grass Killer 41% Glyphosate label (EPA Reg. No. 84009-27) — Source for the Example 3 spot rate (2.5 fl oz per gallon of water) and the 300 sq ft per gallon coverage.Label footer 84009-27 / 3/10/2017 (EPA notification letter dated 2017-03-10)
- Calibration of Pesticide Spray Equipment (Montana State University Extension MontGuide MT 2000-14) — Source for GPA = 5,940 × GPM ÷ (mph × nozzle spacing in) and the 5,940 = 43,560 × 12 ÷ 88 derivation.Extension guide; page accessed 2026-10-23
- CropSmart Glyphosate 41% Extra Safety Data Sheet (rev. 2015-01-27) — Section 9: 'Weigh per gallon: 9.75 lbs. per gallon.' — Supports the 9.756 lb per US gal conversion used for pounds-per-acre rates (4 lb a.i./US gal ÷ 0.41 a.i. by weight; SDS weight per gallon 9.75 lb).SDS revision 2015-01-27
Frequently asked questions
How much 41% glyphosate goes in a gallon of water?
There is no single answer without the label rate and the sprayer carrier volume. The label sets the rate either per acre (broadcast) or per 100 gallons of mix. For a per-acre rate, product per gallon of mix = (rate per acre × 128 fl oz) ÷ carrier volume in gallons per acre. For example, 2 qt per acre at 20 gallons per acre is 64 fl oz per acre, so one gallon of mix carries 64 ÷ 20 = 3.2 fl oz. The calculator shows the same arithmetic for a full tank and for the whole job.
What does per 100 gallons mean on a glyphosate label?
A per-100-gallon rate is tied to the spray mix, not to the ground area: product per tank = rate per 100 gal × tank volume ÷ 100. A 3 fl oz per 100 US gal rate in a 100 US gal tank adds 3 fl oz. The 100 gallons are US gallons (1 US gal = 128 US fl oz). Acres covered still depend on the carrier volume (GPA), so a per-100-gallon label still needs the sprayer gallons-per-acre to convert a tank into acres.
How do I convert a pounds-per-acre glyphosate rate to fluid ounces?
41% glyphosate SL is 41.0% active ingredient by weight and contains 4 lb a.i. per US gallon, so one US gallon of formulated product weighs 4 ÷ 0.41 = 9.756 lb. Therefore fl oz = lb × 128 ÷ 9.756 ≈ 13.12 fl oz per lb of product; a 1.5 lb per acre rate is 1.5 × 13.12 ≈ 19.68 fl oz per acre, and a 1 lb per acre rate is 13.12 fl oz per acre. Check whether the label states pounds of product or pounds of acid equivalent (a.e.): the density conversion applies to pounds of formulated product. The label is the authority on which one it lists.
How many acres does one spray tank cover?
Acres per tank = tank volume in US gallons ÷ carrier volume in gallons per acre. A 100 US gal tank at 20 GPA covers 5 acres. Tank volume can be entered in US or UK gallons; 1 UK gallon = 1.20095 US gallons. Label rates and the per-100-gallon basis are US gallons, so the calculator converts a UK tank size to US gallons before dividing.
Why does the calculator show a partial last tank?
Tanks needed = treatment area ÷ acres per tank, rounded up to whole tanks. When the area is not an exact multiple, the final tank is partly filled: mix volume = total mix needed − (whole tanks − 1) × tank volume. The calculator lists the last tank mix volume and product dose separately so the final load matches the area actually sprayed.
What is the 5,940 sprayer calibration formula?
For a boom sprayer, GPA = 5,940 × GPM ÷ (mph × nozzle spacing in inches). The constant 5,940 = 43,560 × 12 ÷ 88, where 43,560 is square feet per acre, 12 converts inches to feet, and 88 is feet per minute per mph. The calculator can use nozzle flow, ground speed and nozzle spacing to derive the carrier volume, and it also shows the speed that would hit the entered GPA.