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Lawn Fertilizer Calculator

Convert a desired pounds-of-nitrogen rate into actual fertilizer product weight using the first number in the N-P-K analysis.

22-calculator project library Reviewed 2026-07-25Calculations run privately in your browser

Enter project details

Example values are prefilled
Lawn and nutrient rate
sq ft
lb N per 1,000 sq ft
% N

Use the first number in the N-P-K label.

%
Bag and cost
lb
$
$
Location and tax assumptions

The location factor adjusts labor only. Replace all default prices with actual local quotes before purchasing.

A coarse planning adjustment—not a ZIP-code quote.

%

Enter the tax rate that applies to taxable materials.

All default prices are editable examples. Cost scenarios vary the entered plan; they do not represent bids or guarantees.

How to use this fertilizer calculator

Calculate fertilizer product pounds and bags from lawn area, desired nitrogen rate, and bag analysis.

Formula

Required nutrient = area ÷ 1,000 × desired lb N. Product pounds = required nutrient ÷ nitrogen decimal. Multiply by applications and allowance, then round bags up.

Worked example

Example: For 5,000 sq ft at 0.75 lb N per 1,000, one application needs 3.75 lb of nitrogen. A 24% nitrogen product requires about 15.6 lb of fertilizer before overlap.

Accuracy and limitations

Use soil-test and label guidance. This calculator performs quantity math; it does not determine whether a nutrient application is agronomically or legally appropriate.

Frequently asked questions

Which N-P-K number is nitrogen?

The first number. A 24-0-10 product contains 24% nitrogen by weight.

Why divide by the nitrogen percentage?

Only part of the bag is nitrogen, so more total product is needed to deliver the target nutrient weight.

Can I use this for garden fertilizer?

The math works, but gardens often use rates by row, plant, or bed and must follow the product label.

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