Enter your container or bed dimensions
Sample scenarios and outputs
| Scenario | Inputs | Base volume | Adjusted volume | Planning note |
|---|---|---|---|---|
| Raised bed fill | Rectangular, 120×60×25 cm, Qty 1 | 180.00 L | 207.90 L (5% waste, 10% settling) | About 5 bags of 50 L |
| Round nursery pot | Cylinder, 35 cm dia × 30 cm high, Qty 6 | 173.18 L | 200.02 L (5% waste, 10% settling) | Consider top-up after watering |
| Tapered decorative pot | Frustum, 38/25 cm dia × 32 cm high, Qty 2 | 44.78 L | 51.71 L (5% waste, 10% settling) | Blend media in batches for consistency |
Values are illustrative. Your results depend on measured internal dimensions and chosen allowances.
How the calculator computes volume
- Rectangular bed: V = L × W × D
- Round pot (cylinder): V = π × r² × h
- Tapered pot (frustum): V = (πh/3) × (R1² + R1R2 + R2²)
All inputs convert to meters first. Volume is calculated in cubic meters, then converted to liters, cubic feet, and cubic yards.
Adjusted volume applies this factor: Vadj = V × (1 + waste%) × (1 + settling%). Bag count is ceil(Vadj / bag size).
Steps for accurate planning
- Select the shape that best matches your bed or container.
- Choose your measurement unit and enter inside dimensions.
- Set quantity for repeated pots or multiple identical beds.
- Add waste and settling allowances based on your workflow.
- Enter bag size to estimate how many bags to buy.
- Optionally set bulk density for a weight estimate.
- Press Calculate, then export your saved results as CSV or PDF.
Tip: Use the “internal” dimensions. Thick walls, slopes, and drainage layers reduce usable volume.
Why accurate media volume matters
Container and bed performance is strongly influenced by consistent media depth. A 10–20% shortfall can leave roots exposed after watering and settling, while overbuying adds avoidable cost and storage issues. This calculator standardizes planning across shapes, converts units automatically, and outputs liters, cubic feet, and cubic yards for quick purchasing decisions.
Allowances improve real‑world accuracy
Two practical adjustments are included: waste and settling. Waste covers spills, leveling, and trimming around stems. Settling accounts for compaction after watering, vibration during transport, and natural consolidation over time. Many projects use 3–8% waste and 8–15% settling, but heavier mixes may settle less than airy blends.
Bag planning supports budgeting and scheduling
Retail media is commonly packaged in 20–70 L bags, while bulk suppliers quote cubic yards or cubic meters. By converting the adjusted volume into a rounded bag count, you can budget accurately and avoid mid‑job shortages. The saved history also helps compare scenarios, such as deeper beds versus additional containers.
Unit conversions reduce measurement errors
Garden measurements are often taken in centimeters or inches, while supplier labels may list liters and cubic feet. This tool converts all dimensions to meters internally, computes cubic meters, then reports familiar outputs. Keeping a single unit system per job reduces transcription mistakes and makes repeating the same calculation faster.
Weight estimates help with handling and logistics
Bulk density varies widely by blend. Light mixes may be near 250 kg/m³, while denser blends can exceed 600 kg/m³. Weight estimates support transport planning, safe lifting, and container placement. If your mix includes more compost or mineral components, increase density to reflect the heavier material.
| Example | Inputs | Base (L) | Adjusted (L) | Bag plan |
|---|---|---|---|---|
| Large raised bed | 1.50×0.75×0.30 m, Qty 1 | 337.50 | 389.81 (5% waste, 10% settling) | 10 × 40 L bags |
| Small round pots | Ø0.28 m × 0.25 m, Qty 8 | 123.15 | 142.24 (5% waste, 10% settling) | 3 × 50 L bags |
| Tapered planters | Ø0.40/0.25 m × 0.35 m, Qty 3 | 88.65 | 102.39 (5% waste, 10% settling) | 6 × 20 L bags |
Example values are for planning. Always measure internal dimensions and subtract drainage layers if used.
FAQs
1) Which dimensions should I measure for a pot?
Measure the internal diameter and the usable fill height. Thick walls, tapered sides, and a gravel layer reduce usable volume, so inside measurements produce the most realistic result.
2) What waste percentage is reasonable?
Use 3–5% for careful filling and 5–10% for larger jobs, windy conditions, or blending on tarps. Increase waste when you expect more spillage, leveling, or reshaping.
3) Why include settling allowance?
Media consolidates after watering and handling. A settling allowance helps avoid low fill lines and reduces the chance you need an extra bag later for top-ups.
4) How do I pick a bulk density value?
Start around 350–450 kg/m³ for light mixes, then adjust based on your product. Blends with more compost, sand, or mineral components typically weigh more per cubic meter.
5) Do I need to subtract space for plants?
Usually no. Root balls displace some volume, but you often compensate by mounding and later settling. Subtract only for large permanent hardscape inserts or thick drainage layers.
6) Why do my bag labels not match exact liters?
Bag volume can be “loose fill” and may compress during shipping. Moisture also changes density. Use the bag count as a planning estimate and round up if availability is uncertain.
7) Can I use this for mulch or gravel?
Yes. Enter the bed dimensions and thickness, then adjust allowances. For gravel or mulch, use an appropriate bulk density to estimate weight and plan transport more safely.
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