A houseplant pot size calculator takes the guesswork out of repotting. Enter your current pot diameter and root condition to get the ideal upgrade size — too large causes root rot, too small stunts growth.
Your Current Setup
Recommended Pot Size
Enter your pot size and plant type,
then click Calculate.
How to Use the Pot Size Calculator
Choosing the wrong pot size is one of the most common repotting mistakes. Too small and the plant becomes severely root-bound, which stresses the plant and can cause wilting, slow growth, and nutrient deficiency. Too large and the excess soil stays wet too long, causing root rot — especially in low-light conditions where the plant isn't actively drinking.
Step 1: Set Your Units
Toggle between imperial (inches) and metric (centimeters). All inputs and outputs update automatically. Standard nursery pot sizes in the US are measured in inches; European and metric-system countries typically use centimeters.
Step 2: Select Plant Type and Current Pot Size
Choose your plant from the dropdown. The calculator uses growth rate data from each species to calibrate how aggressively to size up. Fast-growing plants like pothos and monsteras can handle larger jumps. Slow growers like ZZ plants and cast iron plants do best with minimal sizing increases. Enter your current pot's diameter — measure across the top opening, not the base.
Step 3: Assess Root Condition
Root-bound means roots are actively circling the pot, visibly pushing through drainage holes, or the root ball holds the shape of the pot when you remove it. Snug means the roots fill the pot but aren't yet stressed. Loose means you're repotting proactively before the plant needs it. Root-bound plants get a larger size jump; proactive repotting suggests a minimal size increase.
Understanding the Recommendation
The calculator recommends a specific diameter and suggests minimum pot depth. It also flags drainage requirements and suggests the best pot material for your plant type. The visual comparison shows your current pot size relative to the recommended size so you can see how much room you're adding to the root zone.
FAQ
Is this tool free?
Yes, completely free with no signup required. Get pot size recommendations instantly.
Is my data safe?
Yes, all calculations run locally in your browser. Nothing is sent to any server.
How much bigger should the new pot be?
For most houseplants, go up by 1-2 inches in diameter (2.5-5 cm). This gives roots room to expand without leaving excess wet soil that stays saturated and causes root rot. Fast-growing plants like pothos, monsteras, and fiddle-leaf figs can go up 2-3 inches. Slow growers like ZZ plants and snake plants should only go up 1-2 inches.
How do I know if my plant is root-bound?
Signs of a root-bound plant: roots circling the bottom of the pot, roots growing out of drainage holes, soil drying out within 1-2 days of watering, plant wilting despite regular watering, roots pushing up above the soil surface, or the pot visibly bulging. Tip the plant gently — if you see a dense mass of roots with little soil visible, it's time to repot.
Does drainage really matter that much?
Drainage holes are non-negotiable for most houseplants. Without drainage, excess water pools at the bottom, drowning roots and creating anaerobic conditions that cause root rot within days to weeks. If you love a decorative pot without holes, use it as a cache pot (outer pot) and keep your plant in a plastic nursery pot with drainage inside it.
What material is best for pots?
Terracotta is ideal for succulents, cacti, and drought-tolerant plants because it wicks moisture away from roots. Plastic retains moisture longer, making it better for moisture-loving tropicals (calathea, ferns) or forgetful waterers. Glazed ceramic falls between the two and works for most plants. Self-watering pots are excellent for moisture-loving plants but can cause root rot in succulents.
When is the best time of year to repot?
Early spring is the ideal time for most houseplants — just as they come out of winter dormancy and before the main growing season. Repotting in spring minimizes transplant shock and gives roots maximum time to establish before winter. Avoid repotting in winter unless the plant is severely root-bound or showing signs of root rot.