Enter your lawn area, your target nitrogen rate and the N-P-K numbers from your fertilizer bag to see exactly how much product to apply and how many bags to buy.
Calculated on your device. Nothing is uploaded to a server.
Under-applying wastes a trip and leaves the lawn hungry; over-applying wastes money and can burn the grass or run off into waterways. A quick calculation from the bag label gets it right the first time.
Enter the nitrogen percentage straight off the guaranteed analysis label for an accurate result.
Don't know your square footage? Calculate it from length and width in one step.
Enter your bag size and see exactly how many bags to pick up at the store.
Fertilizer bags are always labeled by percentage, not by pure nitrogen weight, so a 20-0-0 product is only 20% actual nitrogen by weight. To hit a target nitrogen rate, the calculator first works out how many pounds of pure nitrogen your lawn needs in total: your target rate in pounds per 1,000 sq ft, multiplied by your lawn area divided by 1,000. It then divides that nitrogen weight by the product's nitrogen percentage (as a decimal) to find out how many pounds of the actual product deliver that much nitrogen — a lower percentage product means you need proportionally more of it. A commonly recommended general guideline is about 0.5 to 1 lb of actual nitrogen per 1,000 sq ft per application, though exact rates depend on grass species, climate and time of year, so check your local extension guidance or product label for specifics. If the nitrogen percentage is entered as zero, the calculation would require dividing by zero, so the tool shows a clear validation message instead of a broken result.
Built directly around the N-P-K numbers printed on real fertilizer bags.
A 0% nitrogen entry shows a friendly message, never Infinity or NaN.
Bag count always rounds up so you never come home short.
A commonly recommended general guideline is about 0.5 to 1 lb of actual nitrogen per 1,000 sq ft per application, with total yearly nitrogen varying by grass type and climate. This calculator defaults to 1 lb but you can change it to match your lawn care plan.
It's the guaranteed analysis, three numbers like 20-0-0 showing the percentage by weight of nitrogen, phosphorus (as P2O5) and potassium (as K2O). This calculator only needs the first number, the nitrogen percentage.
Product needed (lbs) equals your target lbs of nitrogen per 1,000 sq ft, divided by the nitrogen percentage as a decimal, multiplied by your lawn area in sq ft divided by 1,000. That converts a nitrogen target into the actual weight of fertilizer product needed.
The calculator shows a friendly message asking you to enter a nitrogen percentage above zero instead of showing an error like Infinity or NaN, since dividing by zero nitrogen has no meaningful answer.
No. If you don't know your square footage, use the length x width helper to calculate it, or type the area directly if you already know it.
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