Fertigation Calculations

Fertigation Calculator

Drip Irrigation Calculation

Enter your fertilizer label (N–P–K format), injection ratio, stock volume, and target nutrient(s). Detailed calculation steps are shown below.

Basic Inputs

Fertilizer Label (N–P–K):
Injection Ratio (e.g., 100):
Stock Volume:

Target Nutrient Inputs

Use Multiple Nutrients

Target N (ppm): (Optional reverse below)
Fertilizer Used (lb):

Fertilizer Weight Calculator

Global Settings

Output Weight Unit: (Final weights will be in this unit.)
Target Unit for Nutrients: (1 mg/L ≅ 1 ppm)

Per-Cycle Fertilizer Mixing

Enter total flow and target nutrient levels, then list your fertilizer sources and assign which fertilizer supplies which nutrient. Detailed calculations for each assignment are shown below. Unlike the “ignore overlaps” version, this code now uses the full composition of each fertilizer.

Total Flow:
Target N (ppm):
Target P (ppm):
Target K (ppm):
Target Other (ppm): (Optional)

Fertilizer Sources

Name	N%	P%	K%

Nutrient Summary

This summary simply sums the percentages from the Fertilizer Sources table. (E.g., if N% cells are 10, 0, and 30, then Sum = 40.00 %.)

Nutrient Assignments

For each assignment row (up to 4), select the nutrient type and choose the fertilizer source. Click “Reset Assignments” to clear all selections (all rows will be set to “None”). (When an assignment is made, the full nutrient composition of the fertilizer is used in coverage calculations.)

Reverse Calculation (Optional)

Enter actual weights (kg) for each assignment row to compute the implied target nutrient levels (ppm).

Irrigation Cycle Calculation

Enter water per cycle, injector ratio, and stock solution volume to determine how many cycles your tank covers.

Water per Cycle:
Injector Ratio (e.g., 50):
Stock Solution Volume:

Reverse Irrigation Cycle Calculation (Optional)

Enter desired cycles to compute required stock volume.

Desired Cycles:

Full Stock Solution Calculation

Multiply the per-cycle fertilizer amounts (from App 2) by the number of irrigation cycles (from App 3).
For example, if per-cycle MAP = 0.10769 kg and cycles = 7.14, then:
Total P-based fertilizer = 0.10769 × 7.14 = 0.76923 kg.

This is an ongoing passion project and gets updated when I have time. Your support is of great value and appreciation.

I often struggle to find this information and find myself having to visit dozens of websites over-and-over again, so consolidating information into one place is my solution to simplify life.