Fertilizer and mixing
Liquid Fertilizer Dilution Calculator
Choose the format printed on the liquid fertilizer label, enter the final batch volume, and get the concentrate amount immediately. Metric and US customary label rates are supported.
Calculator
Match the format on the fertilizer label
Enter the label ratio or rate and the final batch size. The concentrate amount updates instantly.
Before you calculate
What this estimate can tell you
Liquid fertilizer labels may specify a 1:X dilution ratio, milliliters per liter, or fluid ounces per US gallon. These formats can describe the same mixing task, but the numbers are not interchangeable. This calculator converts a label rate; it does not select a fertilizer strength for a plant.
How the fertilizer dilution is calculated
For a 1:X dilution, concentrate volume = final solution volume ÷ X. For a label rate, concentrate volume = final volume × the stated mL/L or fl oz/US gal rate. The calculator normalizes units to milliliters; estimated water volume = final volume − concentrate volume.
Assumptions and limits
- The 1:X mode means one part concentrate in X parts of final solution. If a product defines its ratio as concentrate to water, interpret the label before entering it.
- This calculator is for liquid fertilizer measured by volume. Dry or granular fertilizer requires a mass-based label rate; grams cannot be treated as milliliters without density data.
- Water volume is a practical additive estimate. For the intended final volume, add concentrate first and top up with water to the batch mark.
Worked example
Example: 5 L of fertilizer solution at 1:1000
In this calculator, 1:1000 means one part concentrate in 1,000 parts of final solution. Five liters is 5,000 mL, so the required concentrate is 5,000 ÷ 1,000 = 5 mL. Measure 5 mL of concentrate, then add water until the total volume reaches 5 L rather than adding the concentrate to 5 L of water.
FAQ
Common questions
Does a 1:1000 fertilizer dilution mean one part in 1,000?
Yes in this calculator: 1 mL of concentrate is used to make 1,000 mL of final solution. Some labels instead write a concentrate-to-water ratio, so confirm the product's definition before entering the number.
Which mode should I use for 2 mL per liter?
Choose the label-rate mode, select mL/L, and enter 2. A 5 L final batch would require 10 mL of liquid fertilizer concentrate.
Why should I top up to the final volume?
The target normally describes the final fertilizer solution. Starting with the full water volume and then adding concentrate makes a slightly larger batch. The difference is small at high dilutions, but topping up matches the stated ratio more closely.
Can I use this calculator for water-soluble fertilizer powder?
Not directly. Powder labels commonly use grams per liter or nutrient ppm. Mass cannot be converted to liquid volume without reliable density information, so use the label's weight-based directions and a suitable scale.
Can this calculator be used for pesticides?
No. It is intentionally limited to ordinary liquid fertilizer volume conversions and does not provide pesticide rates or treatment advice. Pesticides must be used strictly according to their approved label and local requirements.
Calculation references
- University of Arkansas: Irrigation Systems & Water QualityUsed to verify that a 1:100 injector ratio describes one unit of concentrate making 100 units of final diluted solution.
- NIST: Approximate Conversions from U.S. Customary Measures to MetricUsed to verify conversions among US gallons, fluid ounces, liters, and milliliters.
- University of New Hampshire Extension: Calculators for Mixing Water-Soluble FertilizerUsed to verify the distinction between a final batch volume and simply adding fertilizer to that full amount of water.