Free calculators for houseplant care. Watering schedules, indoor light level estimates and more, all updated for 2026.
Houseplant care often feels like guesswork, but it does not have to be. Two of the most common reasons plants die are overwatering and insufficient light. Our plant calculators use research-backed models to give you specific, actionable recommendations. The Plant Watering Calculator factors in pot size, plant type, soil mix, and environmental conditions. The Plant Light Calculator estimates lux levels based on window direction and distance, then matches those levels to plant species that will thrive in your space.
Watering frequency depends on several factors: pot size (smaller pots dry out faster), soil type (peat retains more moisture than perlite-heavy mixes), humidity (low humidity increases evaporation), temperature (warmer rooms dry soil faster), and the plant's own water needs. Succulents and cacti prefer to dry out completely between waterings, while tropical plants like ferns and calatheas prefer consistently moist soil. Our calculator weighs all these factors to produce a recommended watering interval in days.
Most houseplants are labeled as needing bright indirect, medium, or low light, but these terms are subjective. Our Light Calculator translates them into measurable lux values. A south-facing window provides roughly 10,000 to 25,000 lux in direct sun, dropping to 1,000 to 5,000 lux just 1 to 2 metres away. North-facing windows typically provide 500 to 2,000 lux. Most common houseplants need at least 1,000 lux for healthy growth. Low-light plants like pothos and snake plants can survive at 500 lux.