Plant Calculators

Plant Watering Calculator

How often (and how much) to water, based on your pot, light, and season.

How this watering calculator works

There's no single "water every 7 days" answer for houseplants, because how fast soil dries out depends on far more than the calendar. This tool starts from your plant's natural water need, then adjusts for the things that actually move the needle: pot size and material, how much light the plant gets, the season, and your room's humidity.

The biggest factors

Pot size: more soil holds more water, so larger pots dry out more slowly.
Material: porous terracotta dries fast; plastic and glazed ceramic stay wet longer.
Light & season: bright light and summer growth speed up water use; winter slows it right down.
Humidity: dry air pulls moisture out of leaves and soil faster.

Always do the finger test

Use the interval as a reminder to check, not to water on autopilot. Push a finger 2-5 cm (1-2 inches) into the soil. If it's still damp, give it another day or two.

Frequently Asked Questions

How accurate is a watering calculator?

It gives you a reliable starting rhythm based on the biggest factors: plant type, pot size and material, light, humidity, and season. Always confirm with your finger or a moisture meter: if the top 2-5 cm (1-2 inches) of soil is still wet, wait a day or two longer.

Why does pot material change how often I water?

Terracotta and unglazed clay are porous and wick moisture out of the soil, so plants in them dry out faster and need water sooner. Plastic, glazed ceramic, and glass hold moisture longer, so you water less often.

Should I water less in winter?

Almost always, yes. Shorter days and cooler temperatures slow growth and evaporation, so most houseplants need noticeably less water from late autumn through winter. This calculator stretches the interval automatically when you choose winter.