Surfactant Adjuvant & Make the Spray Spread & Stick
Wets waxy leaves
Enter spray volume, tank size and the recommended % v/v rate to get the surfactant per tank, total mL, total litres and number of tanks— so spray spreads and sticks on waxy or hairy leaves for better coverage and uptake.
Mix surfactant / adjuvant
Next: measure 37.5 mL per tank and add it after the pesticide is dispersed, with the agitator running, to avoid foaming.
mL/tank = tank L × dose%/100 × 1000. Always follow the adjuvant and pesticide labels — over-dosing surfactant can scorch leaves and increase drift.
Surfactant adjuvant — key facts
- Per tank
- tank volume × (% v/v ÷ 100)
- Typical rate
- 0.1–1% v/v
- 0.25% v/v
- 250 mL per 100 L
- Does
- lowers droplet surface tension
- Best on
- waxy & hairy leaves
- Improves
- coverage & uptake
- Add
- per label mixing order
- Privacy
- Runs in your browser; nothing uploaded
Get the spray onto the leaf, not onto the ground
On waxy or hairy leaves, plain spray beads up and rolls off — much of your pesticide never touches the target. A surfactant or adjuvant lowers droplet surface tension so the liquid flattens, spreads and sticks, wetting the leaf evenly and letting the active ingredient be absorbed. Dosing it right matters: the rate is a small percent by volume of the spray, so surfactant per tank = tank volume × (% v/v ÷ 100).
This tool gives the surfactant per tank, total mL, total litres and the number of tanks from your spray volume, tank size and % v/v rate. Use it to measure adjuvant accurately for knapsack or boom spraying, avoid under- or over-dosing, and plan how much product to buy for the whole job. Pair it with the Spray & Tank Mix, Dilution Ratio and Spray Water Conditioning tools for a complete tank recipe.
Better coverage
Spread and stick on waxy, hairy leaves.
Right dose
Exact surfactant per tank from % v/v.
Plan the job
Total mL and tanks for the whole spray.
Less waste
More active ingredient reaches the target.
Frequently Asked Questions
What does a surfactant or adjuvant do?+
A surfactant (or adjuvant) lowers the surface tension of spray droplets so the liquid spreads out and sticks on the leaf rather than beading up and rolling off. On waxy or hairy leaves that otherwise shed spray, it dramatically improves coverage and the uptake of the active ingredient, making the same dose of pesticide work better.
How is the surfactant dose calculated?+
The dose is a small percentage by volume (% v/v) of the spray solution. Surfactant per tank = tank volume × (% v/v ÷ 100). For example a 1% v/v rate in a 200 L tank needs 2 L of surfactant; a 0.1% rate needs 200 mL. This tool gives the surfactant per tank, total mL, total litres and the number of tanks for your whole spray volume.
What is % v/v?+
Percent volume per volume is the share of the final spray mixture made up of the adjuvant. A 0.25% v/v rate means 0.25 L of surfactant in every 100 L of spray — that is 250 mL per 100 L, or 2.5 mL per litre. Always mix as a percent of the spray volume, not of the product being sprayed.
Why do waxy or hairy leaves need a surfactant?+
Many weeds and crops have a waxy cuticle or hairy surface that repels water, so plain spray droplets bead up and fall off, wasting product. A surfactant breaks that surface tension so the droplet flattens, wets the leaf and holds on long enough for the active ingredient to be absorbed — exactly where you need coverage most.
What rate of surfactant should I use?+
Follow the pesticide and adjuvant labels — typical non-ionic surfactant rates are 0.1–1% v/v depending on the product and target. Too little gives poor wetting; too much can cause excessive run-off or even leaf scorch. When the label gives a rate per 100 L, convert it to % v/v and enter it here.
Does more surfactant always mean better coverage?+
No. Up to the labelled rate, surfactant improves wetting and spread, but beyond it the extra simply runs off the leaf, can foam in the tank, and may damage sensitive foliage. The goal is even coverage to the point of run-off, not dripping — so stick to the recommended % v/v.
When do I add the surfactant to the tank?+
Generally add the surfactant near the end of the mixing sequence, after the pesticide is in and dispersed and with the agitator running, then top up with water — but always follow the product's mixing order. Adding it too early or to a near-empty tank can cause foaming. Spray promptly once mixed.
Does it work for any tank or spray volume?+
Yes — enter your tank size and total spray volume in litres and the % v/v rate, and it gives the surfactant per tank plus the total surfactant and number of tank loads for the whole job. It works for knapsack, boom or any sprayer as long as the rate is expressed as % v/v.
Are the figures precise?+
The arithmetic is exact for the % v/v you enter. Real-world results still depend on water quality, droplet size, leaf type and spray timing. Use clean, conditioned water, keep the agitator running, and calibrate your sprayer — the calculator handles the dose, good spraying practice handles the rest.