The sums growers do by hand, done properly.
Free, no sign-up, and they work offline once the page has loaded. Each one shows its formula, so you can check the arithmetic.
VPD calculator
Vapour pressure deficit from air temperature, humidity and leaf temperature, with a chart of where that sits for each growth stage and the humidity that would put you on target.
Open the VPD calculatorDLI calculator
Daily light integral from PPFD and photoperiod, and the reverse: the PPFD a target DLI needs for your light schedule.
Open the DLI calculatorNutrient mix calculator
How much of each part to add for your reservoir size and strength, plus EC, CF and ppm conversion on the 500, 640 and 700 scales.
Open the nutrient calculatorThey are the numbers GrowRoom watches for you.
GrowRoom's air sensors give it temperature and humidity, so it calculates VPD continuously. Its PAR sensor reads PPFD, and its dosing pumps dispense measured volumes. These calculators do the same arithmetic, for any room.
Ground rules for these tools
- Every result comes from a published formula, shown on the page
- Target ranges are common rules of thumb, labelled as such; your crop and cultivar may differ
- Nothing you type leaves your browser