Grow Light & Environment Calculators
Free, data-first calculators for indoor growers and greenhouse hobbyists. Dial in the environment and the light for basil, lettuce, tomatoes, seedlings and houseplants: work out vapor pressure deficit, daily light integral and canopy PPFD, size a fixture to its coverage area, and price what it costs to run. Every formula is cited to a primary source — FAO, university extension and peer-reviewed lighting research — with imperial or metric units and crop targets built in.
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DLI Calculator
Calculate daily light integral (DLI) from PPFD and photoperiod, and compare it to crop targets for leafy greens, herbs and fruiting vegetables.
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Grow Light Cost Calculator
See how much electricity a grow light uses — cost per month and year, plus an LED-vs-HPS comparison, from wattage, hours per day and your rate.
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Grow Light Coverage Calculator
Find the area a grow light covers at your target PPFD: enter fixture PPF and intensity, get the square footprint in feet and metres for tents or benches.
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PPFD Calculator
Estimate the average PPFD a grow light delivers to your canopy from wattage, photon efficacy, coverage area and utilization, with seedling-to-flower targets.
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VPD Calculator
Calculate vapor pressure deficit (VPD) from air temperature, humidity and leaf temperature, with target kPa ranges by growth stage for tents and greenhouses.