Herbicide & Roundup mixing calculator

Enter the rate from your exact product label, then choose measured water or finished sprayer capacity.

For rates per amount of water only. Area-based rates need area and equipment calibration. Follow all label use limits and precautions.

How much Roundup or 2,4-D per gallon of water?

The brand or ingredient name alone does not tell you the dose. Find the Directions for Use on your exact product label, for your intended site, weeds and equipment. Enter its product-per-water rate in the calculator above.

Match the full product name and formulation. The active-ingredient percentage on the bottle is different from a mixing rate; ready-to-use products may need no dilution.

Look up a US label by product or EPA registration number ↗

Use the label accompanying your container and applicable supplemental directions. For products outside the US, use the label approved in your country.

Scale a label rate to your water amount

Product amount = label rate × water amount. Keep the units together: fl oz per US gallon × US gallons, or mL per litre × litres.

Arithmetic examples only, using two separate example rates. These are not doses for Roundup, 2,4-D or another product. Use the rate on your exact label.

Example: 2 US fl oz per US gallon of water
Water (US gal)	Product (US fl oz)
1	2
2	4
4	8
5	10
10	20
15	30

Example: 10 mL per litre of water
Water (L)	Product (mL)
1	10
2	20
5	50
10	100
15	150

The table amounts are water before adding product. For example, 4 US gallons of water plus 8 US fl oz of product makes about 4.063 US gallons of spray. If everything must fit a 4-gallon sprayer, choose Final spray volume above instead.

US gallons differ from Imperial gallons. The metric and US examples use different rates; they are not unit conversions of each other. Finished volumes assume additive volumes.

Calculate with your own label rate ↑

Does your label use a different rate format?

Product per gallon or litre of water: This calculator supports that label rate. Choose measured water or final capacity as your starting amount; the label’s water basis stays the same.
A percentage, such as 1% v/v: Check whether the label means product as a percentage of the finished spray. A mixing percentage and the bottle’s active-ingredient percentage are different. This calculator needs a per-water rate, so do not enter 1% as the label rate.
Product per acre, hectare or 1,000 sq ft: Tank capacity alone is not enough. You also need the treated area and calibrated spray output, while following the label’s application limits. Penn State’s calibration guide ↗
Product per finished gallon of spray: That denominator differs from a gallon of water. Keep the label’s finished-spray instructions; choosing Final spray volume here changes your starting amount, not the label rate’s denominator.

Help and sources

How much Roundup should I add per gallon?

There is no single amount for every Roundup product. Find the rate on the current label for your exact formulation and enter the amount of product stated per gallon of water.

How much 2,4-D should I use per gallon?

The ingredient name alone does not identify the application rate. Find the Directions for Use on your exact product label for your site, weeds and equipment. If the instructions give product per gallon or litre of water, enter that rate here. A per-acre rate needs area and calibrated spray output instead.

How much product do I need for 2, 4 or 15 gallons of water?

Multiply your label’s product-per-US-gallon-of-water rate by 2, 4 or 15 respectively. For the arithmetic example of 2 US fl oz per US gallon of water, those water amounts need 4, 8 or 30 US fl oz of product. These are example calculations, not product doses. Water amounts are before adding product; choose Final spray volume if the complete mix must fit your sprayer.

What starting amount should I enter?

Choose Measured water if you know the water amount; the product adds to that volume. Choose Final spray volume if the product and water together must fit that amount. In both cases, enter a label rate stated per gallon or liter of water.

Can I enter the active-ingredient percentage or a 1% spray instruction?

No. The bottle’s active-ingredient percentage describes the formulation, while a spray percentage describes a mixing instruction with its own stated basis. This tool requires product per gallon or litre of water. Do not enter either percentage as that rate; use the exact label’s mixing instructions.

Can this calculator handle ounces per acre?

Not by itself. Area-based rates require the treated area, calibrated carrier volume, equipment output and every limit on the product label. Do not convert an ounces-per-acre instruction into a volume-only rate.

EPA introduction to pesticide labels Example of formulation-specific Roundup directions How to calibrate a backpack sprayer EPA label lookup: product names and registration numbers Safety tips for lawn herbicide applications

Roundup is a trademark of its owner. MixByParts is not affiliated with or endorsed by Roundup.

Browse 81 herbicide presets

These separate pages use a rate per finished-spray volume. The tool above uses a rate per water volume, including when you choose finished capacity. Do not interchange these label rates. A preset is not a recommended application rate.