| Shape | Dimensions | Depth | Allowance | Estimated soil |
|---|---|---|---|---|
| Rectangular | 80 × 25 cm | 30 cm | 100% fill, 8% waste | ~65 L |
| Round | Ø 40 cm | 28 cm | 100% fill, 10% waste | ~39 L |
| Oval | 60 × 35 cm | 25 cm | 95% fill, 8% waste | ~45 L |
| Tapered round | Ø 45 → 30 cm | 30 cm | 100% fill, 8% waste | ~35 L |
| Tapered rectangular | 90×30 → 70×20 cm | 35 cm | 90% fill, 12% waste | ~66 L |
1) Compute filled volume
- Rectangular V = L × W × h
- Round V = π × r² × h, where r = D/2
- Oval V = π × a × b × h, where a = A/2 and b = B/2
- Tapered rectangular V = h × (A₁ + A₂ + √(A₁A₂)) / 3
- Tapered round V = π × h × (R₁² + R₁R₂ + R₂²) / 3
2) Apply allowances
Soil = V × (fill% / 100) × (1 + waste% / 100)
3) Convert and estimate bags
- Liters = Soil(m³) × 1000
- Bags = ceil( Liters / BagSize(L) )
- Weight(kg) = Soil(m³) × Density(kg/m³)
- Select the planter shape that matches your container.
- Choose a unit, then enter dimensions and soil depth.
- Set fill percentage if you use a drainage layer.
- Add a waste allowance to cover settling and spillage.
- Choose bag size and optional price to estimate cost.
- Press Calculate and download CSV or PDF if needed.
1) Why soil estimating matters for planters
Accurate soil quantities reduce overbuying, prevent shortages mid‑install, and improve logistics on sites where access, lifts, and staging areas are limited. For planter walls and terraces, a reliable volume estimate also supports loading checks and avoids unnecessary material handling.
2) Planter geometry drives the base volume
Rectangular boxes use length × width × depth, while round and oval planters use circular or elliptical areas multiplied by depth. Tapered planters are treated as frustums, blending top and bottom areas to reflect real shapes commonly used in precast and decorative units.
3) Depth is the most sensitive input
A small change in soil depth can meaningfully shift liters required, especially for wide planters. Measure finished fill height, not the overall planter height, and account for any raised false bottoms, reservoir inserts, or root‑barrier systems.
4) Fill percentage reflects drainage layers and assemblies
Many assemblies include drainage gravel, lightweight aggregate, or modular cells. Use a fill percentage below 100% when those layers displace soil volume, and keep a record of typical build‑ups to standardize estimates across projects.
5) Waste allowance covers settling and top‑off
Potting media settles after watering and installation vibration, and material is often lost during transport and placement. A modest waste allowance helps ensure you can finish leveling and top‑dress without opening an emergency bag at the end of the day.
6) Density links volume to handling and structural checks
Weight depends on bulk density and moisture content. Lightweight mixes are easier to move and can reduce loading on balconies and podium slabs, while heavier blends may improve stability in tall planters but increase handling effort.
7) Bag planning improves procurement and staging
Converting liters into common bag sizes supports purchasing, delivery planning, and storage space. Rounding up to full bags reduces risk, while the cost option helps compare suppliers and choose the most economical packaging for your schedule.
8) Field tips for better inputs and outcomes
Measure internal dimensions, not exterior shells, and note taper directions. If the planter is irregular, approximate with the closest shape and add waste. For repeat installs, save a standard specification for depth, density, and allowances to speed estimating.
1) Should I measure inside or outside planter dimensions?
Use internal dimensions where soil sits. Wall thickness and rims can significantly reduce soil space, especially in precast or double‑wall planters.
2) What fill percentage should I use with a drainage layer?
Estimate the drainage layer height as part of total depth, then reduce fill percentage accordingly. If 5 cm of a 30 cm depth is drainage, use about 83% fill.
3) How do I estimate soil for irregular shapes?
Choose the closest shape (oval or rectangular) using average dimensions. Add a higher waste allowance to cover corners, curves, and measurement uncertainty.
4) Why is the weight estimate different after watering?
Moisture increases bulk density. Wet media can weigh noticeably more than dry media, so treat the dry estimate as a baseline and allow extra margin for saturated conditions.
5) Can I use this for raised beds or planter walls?
Yes. Enter the internal bed dimensions and fill height. For long beds, measure several points and use average width if the wall line is not perfectly straight.
6) How many bags should I order to avoid delays?
Order the calculated rounded‑up bags plus a small buffer if access is difficult. A 5–10% extra allowance is common when delivery windows are tight.
7) Which density value should I enter for potting mix?
If your supplier provides bulk density, use it. Otherwise, start with 800–1200 kg/m³ for many mixes and adjust after a trial fill for your specific product.