Calculation Results
Container Breakdown
| Container | Quantity | Gross fill | Deductions | Base soil | Adjusted soil |
|---|
Bag and Cost Summary
Weight Summary
Mix Ingredient Quantities
| Ingredient | Percentage | Required volume | Estimated cost |
|---|
Checks and Recommendations
Merged Result Summary
Your calculation summary will appear here.
Formula Used
Rectangular planter: V = L × W × H.
Cylindrical pot: V = π × r² × h.
Tapered round pot: V = πh(R² + Rr + r²) ÷ 3.
Tapered square planter: V = h(A₁ + A₂ + √A₁A₂) ÷ 3.
Adjusted soil: Net soil × allowance multiplier.
Gross volume uses the selected container geometry. Deductions remove drainage, existing soil, and root displacement. Allowances then increase the remaining soil purchase quantity.
How to Use
Choose one measurement unit before entering dimensions. Add every container and select its matching shape. Use duplicate when several planters share identical measurements.
Enter drainage, existing soil, and root-ball details carefully. Select a bag size and provide current purchase pricing. Adjust recipe percentages until their total reaches one hundred.
Review the calculated soil, bags, costs, and weights. Read warnings before purchasing materials or moving filled containers. Export the summary for shopping and project records.
Example Data
| Example | Shape | Dimensions | Quantity | Typical purpose |
|---|---|---|---|---|
| Patio pot | Tapered round | 40 cm top, 28 cm bottom, 38 cm high | 3 | Seasonal flowering plants |
| Window box | Rectangular | 80 × 20 × 18 cm | 2 | Herbs and compact flowers |
| Grow bag | Cylindrical | 35 cm diameter, 40 cm high | 4 | Tomatoes and peppers |
Frequently Asked Questions
How much extra potting soil should I buy?
Five to twenty percent usually covers settling and spillage. Large projects often need a slightly higher allowance. Store unopened leftovers somewhere dry and protected.
Why does the calculator round bags upward?
Retailers normally sell complete bags rather than partial bags. Rounding upward prevents an avoidable material shortage. Leftover volume remains visible within the results.
Can I calculate several pot sizes together?
Yes, add one row for each container size. Quantities combine repeated pots within each row. The final total includes every active container.
How are tapered pots calculated?
Tapered containers use frustum geometry instead of cylinders. Top and bottom dimensions must both be entered. This produces a more realistic internal volume.
Should gravel be placed below potting soil?
A drainage layer is optional for many containers. It reduces the space available for plant roots. Reliable drainage holes usually matter much more.
Can garden soil replace potting soil?
Garden soil can compact heavily inside containers. Potting mixes usually provide better aeration and drainage. Follow plant requirements before changing the recipe.
What does root-ball displacement mean?
The existing root ball occupies container space. That volume does not require additional potting mix. Measure it carefully during repotting projects.
Why must recipe percentages total one hundred?
Every ingredient represents part of the complete mix. Missing or excess percentages distort ingredient quantities. Ratio mode automatically converts parts into percentages.
How accurate is the filled weight estimate?
Weight depends on density and moisture conditions. Actual products vary between manufacturers and ingredients. Use saturated weight for conservative handling decisions.
Which bag size offers the lowest cost?
Compare price per litre across available products. Bigger bags are not always automatically cheaper. Delivery charges can change the best choice.
Are the results suitable for purchasing?
The results provide practical planning estimates. Container dimensions and labelled bag volumes may vary. Verify critical quantities before placing large orders.
Important Note
Results depend on entered dimensions and selected assumptions. Product density, compaction, and labelled volumes can vary. Confirm structural limits before placing heavy planters.