Spray Calculator – the right dose for your bed
Product labels give doses in litres per hectare — but your bed is a few square metres. Doing that maths in your head ends in overdosing or a dose that does nothing. The calculator converts the rate to your real area and sprayer volume.
How the dose conversion works
The calculator starts from area: give it your bed dimensions, or a plant count and spacing, and it works out the area in square metres. Then, from the recommended spray-liquid volume per hectare and the product concentration, it computes how much product and how much water to put in the sprayer — no waste, no overdose.
- area mode — enter bed length and width
- plant mode — enter plant count and spacing (in-row × between-rows)
- result — product amount and spray-liquid volume for your sprayer
Spray liquid vs product
The spray liquid is the finished mix of water and product. The label states separately how much liquid to use per area and at what concentration to dissolve the product. The calculator combines both, so you immediately know how much product to measure and how much water to add.
Home-made mixes and ready products
Beyond ready-made products, the calculator handles popular home-made mixes (based on potassium soap, plant extracts or sulfur, for example). For each it scales the ingredient proportions to your chosen sprayer volume.
Spraying safely
- spray in the morning or evening, in still weather
- never spray flowering plants while bees are foraging
- respect the pre-harvest interval (time from spraying to harvest)
- do not raise the concentration "to be sure" — it adds no efficacy and harms the plant and soil
Plan protection treatments alongside sowing and feeding in the app calendar — see also the guides on the blog.
Frequently asked questions
How do I convert a per-hectare rate to m²?
Divide the per-hectare rate by 10,000 to get the amount per m², then multiply by your bed area. The calculator does this automatically once you enter dimensions or a plant count.
How much spray liquid do I need for a bed?
It depends on the recommended liquid volume (l/ha) and the area. For small beds it is usually from half a litre to a few litres — the calculator gives the exact figure.
Does a stronger mix work better?
No. Going above the recommended concentration adds no efficacy but can scorch plants, leave residues and harm the soil and beneficial insects.
Does it handle home-made mixes?
Yes. Alongside ready products, it scales the proportions of popular home-made mixes to your chosen sprayer volume.
Spray Calculator – the right dose for your bed
Every tool runs in your browser and in the mobile app — free, no sign-up, works offline too.
Open this tool in the app →