Pot Size Calculator
Find the recommended pot diameter and soil volume for your plant type and mature size.
Supports inches/gallons and cm/liters.
Recommended Pot Size
Pot sizing depends on the plant type and its mature size. A general rule is that the pot diameter should be roughly 1/3 to 1/2 of the plant’s mature height or spread.
Imperial:
Pot diameter (inches) ≈ Mature size factor × Plant spread
Soil volume (gallons) ≈ (Diameter/2)² × π × Depth / 231
Metric:
Pot diameter (cm) ≈ Mature size factor × Plant spread
Soil volume (liters) ≈ (Diameter/2)² × π × Depth / 1000
General pot size guidelines:
- Herbs/Small plants: 6–8 in (15–20 cm) pot
- Medium houseplants: 8–12 in (20–30 cm) pot
- Large houseplants: 12–18 in (30–45 cm) pot
- Small shrubs/Trees: 18–24 in (45–60 cm) pot
Tips:
- Always choose a pot with drainage holes
- Go one size up (2 inches / 5 cm) when repotting
- Terracotta dries faster, plastic retains moisture longer