liminfoFertigation Calculator
Free web tool: Fertigation Calculator
N Fertilizer (kg)
56.775
P Fertilizer (kg)
37.850
K Fertilizer (kg)
75.700
Injection Rate
0.100 GPM
Dilution Ratio
1:100
Est. Run Time
126.2 hours
Add calculated fertilizer amounts to stock tank. Injection rate = System flow / Dilution ratio.
About Fertigation Calculator
The Fertigation Calculator helps growers precisely determine how much N (nitrogen), P (phosphorus), and K (potassium) fertilizer to add to a stock tank based on target ppm concentrations, tank volume, and dilution ratio. It supports both gallon and liter units, making it equally useful for US-based growers and metric-system operations worldwide.
This tool is essential for hydroponic farmers, greenhouse operators, and drip-irrigation specialists who need to maintain exact nutrient concentrations in their irrigation water. By entering the target nutrient levels in ppm, the stock solution percentages, and the system flow rate, users can instantly see the required fertilizer weights in kilograms, the injector flow rate in GPM, and the estimated system run time in hours.
Under the hood, the calculator converts tank volume to liters, applies the dilution ratio to determine the effective nutrient demand, and divides by the stock solution concentration to yield the mass of each fertilizer needed. The injector rate is derived from the system flow rate divided by the dilution ratio, and the run time is estimated from tank volume divided by injector rate, giving operators a complete picture of a single fertigation event.
Key Features
- Calculates N, P, and K fertilizer amounts (kg) required for a full stock tank fill
- Supports gallon and liter tank units with automatic conversion to liters
- Accepts target nutrient concentrations in ppm for nitrogen, phosphorus, and potassium independently
- Takes stock solution percentages (%) to account for varying fertilizer concentrate strengths
- Computes injector flow rate (GPM) based on system flow rate and dilution ratio
- Estimates total run time (hours) for draining a stock tank at the calculated injection rate
- Displays dilution ratio (1:X) confirmation alongside injector rate for quick cross-check
- 100% browser-side computation — no data is sent to any server
Frequently Asked Questions
What is fertigation?
Fertigation is the practice of delivering dissolved fertilizers through an irrigation system directly to the plant root zone. It is widely used in hydroponics, greenhouse production, and precision drip-irrigation agriculture because it allows nutrient application to be precisely timed and dosed.
How does the calculator determine how much fertilizer to add?
It converts the tank volume to liters, multiplies by the target ppm divided by 1,000,000 to get the mass in kg, then multiplies by the dilution ratio, and finally divides by the stock solution concentration fraction. This gives the exact mass of each fertilizer concentrate needed to fill the stock tank.
What is a dilution ratio in fertigation?
The dilution ratio (1:X) represents how many parts of clean water are mixed with one part of stock solution. For example, a 1:100 ratio means one liter of stock solution is diluted into 100 liters of irrigation water. The higher the ratio, the more dilute the final nutrient solution.
What units does the calculator use for tank size?
You can enter tank size in either US gallons or liters. When gallons are selected, the calculator automatically converts to liters (1 gallon = 3.785 liters) before computing nutrient doses, so all outputs are in consistent metric units.
How is the injector flow rate calculated?
The injector flow rate (GPM) equals the main system flow rate divided by the dilution ratio. For example, if the system flows at 10 GPM and the dilution is 1:100, the injector must deliver 0.1 GPM of stock solution to achieve the correct concentration.
Who typically uses a fertigation calculator?
Greenhouse growers, hydroponic facility managers, irrigation agronomists, hobby hydroponic enthusiasts, and commercial vegetable and flower producers all rely on fertigation calculators to formulate consistent nutrient programs and avoid over- or under-feeding crops.
Can I use this calculator for any NPK fertilizer?
Yes. The tool is fertilizer-brand agnostic. You simply enter the percentage of N, P, or K in the stock solution for whichever fertilizer concentrate you are using, and the calculator adjusts the required mass accordingly.
What does the estimated run time mean?
Estimated run time is the number of hours it will take to empty a full stock tank at the calculated injector flow rate. It helps growers plan maintenance schedules and know when to prepare the next batch of stock solution.