Measure diameter and height to size containers. Pick tapered or straight walls, then calculate instantly. Download results for better mixes, spacing, and growth planning.
| Pot type | Top diameter | Bottom diameter | Height | Estimated volume |
|---|---|---|---|---|
| Tapered nursery pot | 30 cm | 22 cm | 28 cm | ~15.8 L |
| Small herb pot | 18 cm | 12 cm | 16 cm | ~3.0 L |
| Straight-sided bucket | 25 cm | — | 25 cm | ~12.3 L |
This calculator treats a straight pot as a cylinder and a tapered pot as a frustum. Measurements are converted to centimeters, then volume is computed in cubic centimeters.
R is the top radius, r is the bottom radius, and h is height. Output conversions use 1 L = 1000 cm³.
Soil estimate applies voids and settlement adjustments to help purchasing.
Pot volume influences watering frequency, nutrient buffering, and root temperature stability. Small volumes dry quickly and swing in salinity after feeding. Larger volumes store moisture longer and allow deeper rooting, which supports steady growth and fewer stress events in warm weather. Matching volume to crop demand reduces runoff and improves uniformity.
Measure inside diameters, not the outside lip. For tapered pots, take a top diameter at the rim’s inner edge and a bottom diameter at the inner base. Measure height from the internal floor to the rim, then average two diameter readings taken at right angles. If the base has a dome, measure from the lowest planting surface rather than the drainage feet.
Nursery pots are typically tapered, so their true capacity is lower than a same top diameter cylinder. This calculator models tapered pots as a frustum, capturing the changing radius through height. Straight sided containers, such as buckets, are modeled as cylinders for direct capacity estimates. Selecting the correct shape improves comparisons when you are deciding between two pot styles with similar top openings.
Use the liters output to plan bagged media or bulk mixes. The voids adjustment reflects air space in bark or perlite blends, while the settlement allowance adds extra for watering and compaction. These controls reduce under buying and help maintain consistent fill levels after the first irrigation. For repeatable recipes, convert liters to parts by volume and keep a log for each mix.
Record volumes for each pot size and standardize fertilizer rates per liter. Pair top surface area with mulch depth to estimate mulch quantities. When upsizing, compare old and new volumes to predict watering changes. Export results to build a quick reference for seasonal planting runs. For containers that sit outdoors, consider adding a drainage layer only when needed, because it can reduce root zone volume and increase drying.
Use inside measurements. Outside diameters include wall thickness and can overstate capacity, especially on heavy planters. If the rim is thick, measure slightly below the lip for a realistic inside diameter.
Most nursery containers are tapered. Choose tapered when the bottom opening is smaller than the top. If the sides are nearly vertical, straight sided will be close enough for planning soil quantities.
Soil mixes contain air spaces and can settle after watering. The voids setting accounts for mix structure, and settlement adds extra for topping up. Set both to zero if you want pure geometric volume only.
Conversions are mathematical and consistent. Differences usually come from measurement error, irregular pot shapes, or interior steps and domes. For best results, measure carefully and use inside dimensions.
Yes, as long as the container is roughly round and you can measure diameter and height. For very shallow bowls, small height errors have a large effect, so recheck height and average several readings.
Top area helps estimate mulch, compost top dressing, and evaporation exposure. Combine area with a target mulch depth to estimate material volume, and use it to compare how quickly different pot sizes may dry.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.