Use a 3-step bucket walk test to measure how much water your sprayer puts down over a measured strip. Then use your own label information to plan the job.
Fill your sprayer to a known volume, mark out a test strip, walk it at your normal spraying pace and pressure, then measure what's left.
Uses the output rate from step 1 to work out total water and tank fills for your job area.
Enter the rate from your own product's label. This tool covers mL or g per litre of water, and mL or g per 1 m², 10 m², 100 m² or hectare. If your label uses a different unit or area (for example per hundred litres of water, or a rate per hectare that isn't a product-per-area figure), convert it to one of these forms first; this tool does not suggest a rate or do that conversion for you.
A herbicide or fertiliser label states a rate like "2.5 mL per litre of water" or "50 mL per 100 m²", and both forms assume you already know how much water your sprayer actually puts down over a given area. Two sprayers walked at the same pace with the same pressure setting rarely deliver the same amount, a different nozzle, a different pump, even a fuller or emptier tank changes the output. The width of the pattern you actually spray matters too, a wider fan covers more ground per pass at the same walking pace, which lowers the output per square metre even though nothing about the tank or pump changed. Guess at that figure instead of measuring it and the mixed rate is built on an amount of water your sprayer isn't actually delivering, which throws off the real dose per square metre even when the mixing arithmetic is done correctly.
A bucket walk test measures your sprayer's real output directly: fill it to a known volume, walk a measured test strip at your normal pace and pressure, then measure what's left. Water for the job, tank fills and the per-area product mode all build on that one measured number. The per-litre dilution mode is the exception, it only needs your tank capacity and the label's own rate, independent of the calibration.
Start with 10 L in the tank, walk a 10 m × 1 m test strip (10 m²), and 8 L is left, 2 L used. That's an output rate of 0.2 L/m², or 20 L per 100 m², or 2000 L/ha.
For a 500 m² lawn at that rate, the job needs 100 L of water total. A 15 L tank fills 7 times: 6 full tanks plus a 10 L partial last fill. That same 0.2 L/m² output rate means one full 15 L tank covers 75 m² of ground.
If the label gives a per-litre dilution, say 2.5 mL per litre of water, that's 37.5 mL of product per full 15 L tank. If the label gives a per-area rate instead, say 60 mL per 100 m², that's a different figure: 45 mL per tank (because a tank covers 75 m², not 100 m²) and 300 mL of product for the whole 500 m² job.
Each step builds on the output rate the bucket walk test measures. Nothing here assumes a rate, a product or a tank size, every value comes from what you enter.
| Step | Gives you | Formula |
|---|---|---|
| Bucket walk test | Output rate (L/m²) | (start L − remaining L) ÷ test strip area (m²) |
| Job water | Total water for the job | job area (m²) × output rate (L/m²) |
| Tank fills | Full fills + last partial fill | ⌊total water ÷ tank capacity⌋ full tanks, plus the remainder as a last partial fill (an exact multiple has no partial fill) |
| Area per tank | Ground one full tank covers | tank capacity (L) ÷ output rate (L/m²) |
| Product per tank (per litre) | Product for one tank | label rate (per L) × tank capacity (L) |
| Product per tank (per area) | Product for one tank | label rate × (area per tank ÷ label's rate area) |
| Total product (per area) | Product for the whole job | label rate × (job area ÷ label's rate area) |
Guessing at your sprayer's output instead of measuring it affects the two label-rate modes differently. In per-area mode, an inaccurate output figure changes how much ground the tool thinks one tank covers: underestimate the real output and the tool overstates that ground, so the mixed batch ends up doing more per square metre than the label rate intends over the ground it actually treats; overestimate it and the reverse happens, less per square metre than the label rate intends. In per-litre mode the mix concentration itself doesn't depend on the calibration at all, it's just the label's own rate applied to your tank capacity, but the job water total and tank-fill count still do, so an inaccurate figure there means running short of mixed product before the job is done, or mixing more than the lawn needs. Neither error shows up on the day, a sprayer doesn't announce that it's putting down more or less than you think, it only shows up later in how much ground actually got covered or how the lawn responds. Both come from the same cause: an assumed output figure that was never actually measured against your own gear.
For a per-area label rate, you can, once you know your sprayer's real output. That rate assumes a known amount of water goes down over a given area; without calibrating your own sprayer first, the product-per-tank and job total this tool works out don't match what your equipment actually delivers. A per-litre dilution rate is different, it's just the label's rate applied to your tank capacity, independent of calibration, but the water and tank-fill planning for the job still needs it.
Knapsack, backpack or boom sprayers with a fillable tank, yes, the bucket walk test measures whatever your setup actually puts down as long as you can fill it to a known volume, walk a measured test strip, and measure what's left. A hose-end sprayer that draws from a running hose has no finite tank volume to measure this way, this tool doesn't apply to that type.
Use the "Per area" option in step 3. Product per tank uses the area one tank covers, calculated from steps 1 and 2. Total product for the whole job is worked out directly from the label's rate and your job area, independent of tank coverage.
Walk it at the same pace and pressure you'll use for the real job. The bucket test measures whatever pace and pressure you actually walk it at, so the closer that matches your normal spraying, the closer the calibration matches the real job.
No. It's free, with no sign-up and no login.
No. It only does the arithmetic on numbers you enter from your own product's current label. Always follow label directions and any relevant permit conditions.
A Free LawnSuite account lets you record applications and view forecast wind, rain and heat to help choose a spraying window. Check the current label and conditions at the lawn before spraying. Copy your results before leaving; creating an account does not transfer this calibration.
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