Plant Watering Calculator

A 6-inch (15 cm) pot holds roughly 1 litre of soil. In summer, a moderately thirsty plant in average soil needs about 150–200 ml per watering. In winter the same plant may only need 50–80 ml. This calculator uses pot diameter to estimate soil volume, then applies plant-type and season multipliers to give you a personalised amount.

Sandy soil drains very quickly — water passes through before roots can absorb it, so you need to water more frequently but with less water each time. Clay soil holds water for a long time and can cause root rot if overwatered. Loamy soil strikes the perfect balance. This calculator adjusts the per-session water volume and suggested frequency based on soil drainage speed.

Succulents store water in their leaves and can go 2–3 weeks without watering in winter. Tropical plants like pothos, peace lilies, and calatheas prefer consistently moist (not wet) soil and may need water every 4–7 days in summer. The 'Plant Type' selector in this calculator adjusts the watering multiplier: 0.4× for succulents and cacti, 1.4× for tropicals.

Yes — dramatically. In summer, higher temperatures and longer daylight hours increase evaporation and plant transpiration, meaning soil dries out 2–3× faster. In winter, most houseplants enter a semi-dormant state and their water uptake slows significantly. Watering the same amount year-round is one of the most common mistakes that leads to winter root rot.

The finger test means pushing your finger 2 cm (1 inch) into the soil — if it feels dry at that depth, it's time to water. This calculator gives you a target volume and schedule, but you should always use the finger test to confirm before watering, especially in winter or during cloudy periods when soil dries much more slowly than on sunny days.