Fertilizer Ratio Calculator
Calculate fertilizer needs based on NPK ratio, garden area, and application rate. Find out how many bags you need and the cost.
Inputs
%
%
%
sq ft
lbs N/1000 sq ft
lbs
$
Results
Total Fertilizer Needed
10 lbs
≈ 2 bags of sugar
NPK Ratio10-10-10
Nitrogen (N) Delivered1 lbs
Phosphorus (P) Delivered1 lbs
Potassium (K) Delivered1 lbs
Bags Needed1
Total Cost$20.00
Cost per Sq Ft$0.02
How to Use This Calculator
- Read the NPK label on your fertilizer bag and enter the three numbers into the N%, P%, and K% fields.
- Enter your total garden area in square feet and the desired application rate (lbs of nitrogen per 1,000 sq ft — typically 1 lb for lawns).
- Input the bag weight in pounds and cost per bag so the calculator can estimate the number of bags and total cost.
- Review Total Fertilizer Needed (lbs) and Bags Needed to plan your purchase.
- Check the individual nutrient delivery weights (N, P, K in lbs) to verify you are meeting your soil's nutritional goals.
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