Calculators Sprayer calibration
How much goes in the sprayer?
Labels are written per hectare. Your knapsack is not a hectare, and how much water it lays down depends on your nozzle, your pressure and how fast you walk. Measure it once and every label rate turns into a number you can actually use.
Fill it to a mark you can read again. Half full is fine.
Mark out a patch and spray it exactly the way you would spray the lawn. Same pace, same overlap.
If the label only gives litres per hectare, divide by 100 to get mL per 100m².
Two people with the same sprayer and the same nozzle can put down wildly different amounts of water, because one walks faster than the other. That is the whole reason this test exists. It is measuring you as much as the equipment.
Do it with plain water on a driveway or a spare bit of lawn. Redo it if you change the nozzle, and that is about it.
The longer version
Why the water volume does not change the dose
The amount of product is set by the label rate and the area you are covering. The water is only a carrier. More water means a more dilute mix spread over the same area, so the same amount of chemical still lands on the grass. That is why calibration matters for coverage rather than for strength.
It does still have limits. Too little water and you get poor coverage and streaking. Too much and it runs off the leaf, which matters for anything that works through the foliage.
Spot spraying out of a handheld bottle
Once you know your rate, the per-litre figure falls straight out of it, and it does not change with bottle size. A rate of 10 mL per litre is 10 mL in a one litre bottle and 20 mL in a two litre bottle.
Read the label
Everything here is arithmetic on the numbers you type in. The label is the authority on rates, timing, withholding periods and what the product can legally be used on. Check it.
Your lawn, every product, one number
This gives you one tank. It cannot remember your lawn, your products, or when you last sprayed. The app already knows your lawn's size and grass type, so it turns any label rate into what actually goes in your sprayer or spreader. Log it once and it tells you when it is due again.
Free. No account. No Pro tier. Nothing is locked and nothing is paywalled, and your lawn data never leaves your phone.