SwardOps
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Sprayer calibration calculator: what’s your water volume?

Catch each nozzle for 60 seconds, measure your width, know your speed. Get your output in L/ha for boom, handgun or knapsack. It’s the number every label rate depends on.

Knapsack? Use 1 nozzle, your lance’s catch-test output, the band width you wet per pass, and a walking speed.

Your sprayer applies

150 L/ha

≈ 9.6 ha covered per hour24 L/min total flow

Now take that figure into the tank-mix calculator →

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The maths is the easy half. The record is the legal half.

SwardOps crews log every application from their phone (product, rate, water volume, weather, operator) with COSHH sheets attached. Inspector-ready without the ring binder.

Start free trial →

Calibrated? Now mix the tank right.

Take your L/ha into the tank-mix calculator and get exact product per tank.

Tank-mix calculator →Start free trial

Calibration questions, answered

How do I calibrate a boom sprayer?
Measure your wetted spray width, catch each nozzle’s output in a jug for 60 seconds (in ml), and time your forward speed. Then: L/ha = (total flow in L/min × 600) ÷ (speed in km/h × width in m). This calculator does that arithmetic for you. Re-check nozzles regularly. Worn tips over-apply.
How do I calibrate a knapsack sprayer?
Same principle at walking pace: catch your lance’s output for 60 seconds, measure the band width you wet per pass, and use a steady walking speed (about 3–5 km/h). Alternatively, spray a measured plot with plain water and scale up: L/ha = litres used ÷ plot m² × 10,000.
What water volume should I be applying?
Most UK amenity and grassland labels specify 100–400 L/ha. Your product label is the legal document. If your calibrated output falls outside its stated range, adjust speed, pressure or nozzle size until it doesn’t.
Why does calibration matter legally?
Under UK law professional spray operators must apply products as per the label, keep application records, and (under the Official Controls regime) have equipment tested. An uncalibrated sprayer means wrong doses, which is a compliance failure and wasted chemical.