Enter the application rate from your fertiliser or other product label and your lawn area to work out the amount for that area. It scales the rate on your product's label to the area you measured.
Product labels quote a rate per a fixed area, commonly per 100 m² or per hectare (10,000 m²), because that's a convenient round number for the label to print, not because it matches your lawn. A home lawn is typically somewhere between 40 m² and 400 m², rarely a round number and rarely a neat fraction of the label's own area unit. Scaling the label's rate to your actual measured area, rather than eyeballing a fraction of the printed number, is what tells you the real amount for the ground you're treating.
The same problem shows up whichever direction the mismatch runs. A 30 m² garden bed treated with a rate meant for a 100 m² area needs less than a third of the printed figure, scaled down, not the printed figure itself. A 350 m² back lawn treated with the same 100 m² rate needs three and a half times it. Mental arithmetic on an awkward area, or rounding it to "close enough" to the label's own unit, is exactly the guesswork this tool replaces with the actual scaled figure.
Say your product's label gives a rate in grams per 100 m². For a 500 m² lawn the tool multiplies that rate by 5 (500 ÷ 100) to show the amount, with a paired unit where available.
Some rates land on a much smaller figure once scaled down to a small area. A per-hectare label rate applied to a small garden bed can scale to a figure like 0.001 kg, which most kitchen scales can't read; the paired scale shows the same amount as 1 g, the figure you'd actually measure. Both come from the same unrounded amount: this tool works out the scaled quantity first and only then rounds each scale for display, so a small result keeps its leading digit instead of rounding away before the second scale is worked out.
The denominator is whatever area the label states its rate "per". Multiplying by your measured area, divided by this figure, scales the rate to your ground.
| Label says "per" | Area this equals |
|---|---|
| 1 m² | 1 m² |
| 10 m² | 10 m² |
| 100 m² | 100 m² |
| hectare | 10,000 m² |
Where a paired value is shown, both figures come from the same unrounded amount.
| Axis | Scales, largest to smallest |
|---|---|
| Mass | kg → g → mg |
| Volume | L → mL |
mL is the smallest volume scale this tool uses: a result already under 1 mL has no smaller home-usable unit to pair with, so it's shown alone. The same applies at the largest scale on either axis (kg, L) for a result of 1000 or more.
Applying less than the label's rate across your measured area under-treats whatever the product is meant to fix, weeds, disease or a nutrient gap keep going because the ground never got the amount the label assumes. Applying more than the rate over-treats it, more product spread over the same ground than the label calls for. Measuring the area lets the calculator scale the label rate to that area. Often the mistake isn't obvious on the day, the effect of an under- or over-scaled rate can take time to show up in how the treated area responds, rather than anything visible at the time of application.
Where a paired value is shown, both figures come from the same unrounded amount.
This tool takes rates in mL, g, L or kg per 1 m², 10 m², 100 m² or hectare. Convert other units to one of these forms before entering a rate. For a rate per litre of water, use the Sprayer Calibration tool's Per litre of water mode, which works from the label rate and your tank capacity.
Yes. Toggle to "Length × width" and enter the two measurements; the tool multiplies them into a total area the same way the direct-entry option works.
No. The tool works out the scaled quantity first and rounds only for display, so a small but real amount keeps its leading digit instead of rounding away to zero.
No. It's free, with no sign-up and no login.
It scales the rate from your own product's current label to your measured area, so the label stays the source of every rate.
A Free LawnSuite account lets you save your lawn zones and calculate a single-product dose from the label rate you enter and your saved zone area, with a weather outlook and treatment log. My Shed products and saved label rates require Pro. Copy this result before leaving, then enter your zone area once in LawnSuite to reuse it in later calculations.
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