This page collects the UAorganic tools that do the math for you: fertilizer doses, acid for your water alkalinity, and reference charts to check the result against. All of them are free and run right in your browser.
Hydroponics calculators
NPK fertilizer calculator
Pick a crop and growth stage, enter a reservoir volume from 1 to 1,000 L, and the calculator gives you grams of fertilizer for parts A, B, and C along with the mixing order. The same app includes seeding rates, diagnostics, and a concentrate recipe. You can install it on your phone as an app without the App Store, and it works offline.
Open the NPK calculator · step-by-step guide to mixing a nutrient solution
Hydroponic acid dosing calculator
Works out how many milliliters or fluid ounces of nitric, phosphoric, or sulfuric acid to add to a reservoir to neutralize water alkalinity. It accepts alkalinity in ppm CaCO₃, meq/L, °dKH, or ppm HCO₃⁻, with separate modes for a recirculating reservoir and for injector irrigation. It also shows how much nitrogen, phosphorus, or sulfur the acid adds to your solution.
Hydroponic acid dosing calculator
Stock solution dilution calculator
Works out how many milliliters or fluid ounces of each stock part, A and B or A, B, and C, go into a reservoir of any size based on concentrate strength. It checks whether your stock matches the injector ratio and shows the EC to expect at the outlet. For top-ups, it calculates how much concentrate to add to a partly full tank to hit your target EC.
Stock solution dilution calculator
DLI and PPFD calculator
Works out how many moles of light per day a grow light delivers at a given PPFD and photoperiod, and compares that with the range for lettuce, microgreens, basil, or tomato. It shows the PPFD or hours needed to hit the range. For greenhouses, it takes your outdoor DLI and glazing loss and calculates how many hours of supplemental light to run.
VPD calculator
Works out vapor pressure deficit from temperature and humidity, for the air and for the leaf, and shows the dew point. In reverse mode, it tells you what humidity to hold at your temperature to keep VPD within a target range.
Microgreens business math
Break-even calculator
Works out how many trays of microgreens you need to sell each month to cover rent, depreciation and wages, how many shelves that takes, and what is left if you sell everything.
Reference charts for microgreens and hydroponics
Microgreens seeding rates
How many grams of seed to sow on a standard 11×19 cm (4.3×7.5 in) berry box: a chart for about 70 crops with seed amounts, sowing density, and timing. Why one rate does not fit every crop, and how to find your own working rate, is covered in the wiki on microgreen seeding rates.
Microgreens seeding rates chart
Target EC and pH by crop
Working EC and pH values for common hydroponic crops, pulled together from our articles and microgreen cards. The numbers hold for a healthy plant mid-stage at a normal root-zone temperature, and the chart lists the rules for when to shift them.
Where to start: water, acid, fertilizer
- Get your water alkalinity from a lab report or a KH drop test. The wiki on water alkalinity explains why it matters.
- Calculate the dose in the acid calculator and add the acid to plain water.
- Calculate fertilizer in the NPK calculator, account for the nitrogen, phosphorus, or sulfur the acid added, and add parts A → B → C.
- Check the solution EC and pH against the chart for your crop.