Organic Fertilizer Requirement Calculator

Calculate the exact amount of fertilizer needed for a healthy, thriving organic garden.

Total Fertilizer Needed

0.00 lbs

Based on your area and nutrient needs.

How to Use the Calculator

This tool simplifies fertilizer application by determining the total amount of product you need based on three key factors:

Garden Area: Enter the total square footage of your garden or use the length and width fields to calculate it automatically.
Nutrient Rate: Select a preset based on what you’re growing, or enter custom values from a soil test. This is the target amount of nutrients (in lbs) you want to apply per 1000 square feet. Nitrogen is often the primary factor for calculation.
Fertilizer N-P-K: Enter the three numbers listed on your fertilizer bag. These numbers represent the percentage of Nitrogen (N), Phosphorus (P), and Potassium (K) in the product.

Frequently Asked Questions

How do I determine my soil’s nutrient needs?

The most accurate way is to get a soil test. Many local extension offices provide this service. Alternatively, you can use general recommendations based on the types of plants you are growing. Our calculator provides presets for common garden types like vegetables and flowers.

What does the N-P-K ratio on fertilizer mean?

N-P-K stands for Nitrogen (N), Phosphorus (P), and Potassium (K). The numbers represent the percentage of each nutrient in the fertilizer by weight. For example, a 10-10-10 fertilizer contains 10% Nitrogen, 10% Phosphorus, and 10% Potassium.

Can I use this calculator for both granular and liquid organic fertilizers?

This calculator is primarily designed for granular fertilizers, which are measured by weight (lbs or kg). For liquid fertilizers, you should follow the dilution and application rates specified on the product label, as they are measured by volume.

How often should I apply organic fertilizer?

Application frequency depends on the type of fertilizer and the needs of your plants. Slow-release organic fertilizers may only need to be applied once or twice a season, while others might require more frequent application. Always check the product’s instructions.

Explore more of our soil and garden calculators to perfect your cultivation techniques: