Measure beds, pits, and rings with simple inputs. Get cubic meters, yards, and bag counts fast. Add waste and shrink allowances for confident ordering.
| Scenario | Shape | Dimensions | Depth | Target volume | Notes |
|---|---|---|---|---|---|
| Raised bed top-up | Rectangular | 3.0 m x 1.2 m | 0.08 m | 0.288 m3 | Good for annual soil refresh. |
| Garden bed fill | Rectangular | 4.0 m x 2.0 m | 0.20 m | 1.600 m3 | Add 10-15% for waste and leveling. |
| Tree ring | Circular | Diameter 2.0 m | 0.10 m | 0.314 m3 | Keep compost away from trunk flare. |
| Trapezoid bed | Trapezoid | L 5.0 m, a 2.0 m, b 1.0 m | 0.15 m | 1.125 m3 | Useful for tapered landscape beds. |
Rectangular: V = L x W x D
Circular: V = pi x r^2 x D, where r = diameter/2
Trapezoid plan: Area = (a + b)/2 x L, then V = Area x D
Waste allowance: V_order = V x (1 + waste%)
Shrink allowance: if volume shrinks by s, then V_start = V_order / (1 - s)
Unit conversions: 1 m3 = 1000 L = 35.3147 ft3 = 1.30795 yd3
Compost is usually priced by cubic yard, cubic meter, or by the bag. Ordering short can delay placement, while over-ordering creates disposal and handling costs. Volume planning also supports access control: you can schedule deliveries when crews, wheelbarrows, and staging space are available.
Depth is the biggest driver of required volume. For top-dressing lawns or finished beds, many crews apply 50–75 mm (about 2–3 in). For improving soil structure in new beds, 100–150 mm (4–6 in) is common. For fill in raised beds, depths of 150–300 mm may be used.
Bulk density varies with moisture, screening, and wood content. A practical field range is roughly 400–900 kg/m3. Multiply density by volume to estimate mass for lifting plans and delivery constraints. Example: 1.0 m3 at 650 kg/m3 weighs about 650 kg, affecting handling and ground loading.
Real projects rarely match clean geometry. Edges are uneven, grades change, and some material is lost to spillage or compaction. A 5–10% waste allowance is typical for small beds with careful placement. Use 10–15% for larger landscape areas, irregular borders, or when blending compost into existing soils.
Compost settles after watering, foot traffic, and time. If you are targeting a finished depth after settlement, include a shrink allowance. Light settling might be 5–10%; wetter or less screened material can settle 10–20%. The calculator estimates a starting volume that should deliver your final target after shrink.
Bagged compost is convenient for small jobs and tight access, but it often costs more per unit volume. Standard bags include 40 L (0.04 m3) and 1 ft3 sizes. Bulk delivery is efficient when staging is possible. Use the bag counts to compare options and to reduce jobsite packaging waste.
Conversion helps procurement: 1 m3 equals 1.30795 yd3 and 35.3147 ft3. Many landscape trucks carry about 2–6 yd3, while larger dump trucks may handle 8–12 yd3 depending on local limits and material moisture. Match the computed yd3 to truck capacity and plan one or two smaller drops if space is limited.
After spreading, spot-check depth with a ruler at multiple points, especially near edges. Rake to uniform thickness, then water to settle and reveal low areas. If compost is used as mulch, keep it away from stems and trunk flare. Re-measure after settlement to confirm your finished depth targets.
For surface refresh, 50–75 mm is common. For soil improvement, 100–150 mm works well. Raised-bed fills may use 150–300 mm depending on design and available material.
Use 5–10% for simple rectangles and careful placement. Choose 10–15% for irregular shapes, sloped grades, blending into soil, or when access limitations increase spillage and rehandling.
Shrink allowance estimates settling after watering and time. If you need the finished depth to meet a target, add 5–20% depending on moisture and screening. The calculator back-calculates a starting volume.
Density converts volume to weight. Weight affects lifting plans, delivery limits, and ground loading. Moist, fine compost is heavier than dry, woody compost, so the same volume can behave very differently on site.
Yes. The tool converts ordering volume to common bag sizes. It assumes 40 L and 1 ft3 by default, and you can override bag size if your supplier uses a different label.
Break the area into rectangles, circles, or trapezoids, calculate each volume, then add them. For curved edges, measure average widths or use several short segments for better accuracy.
The geometric volume is the same, but density and settlement can differ. Compost often settles more than mineral soil. Use a realistic density and shrink value for the specific product and moisture level you will install.
Accurate compost volumes keep projects clean, fast, and affordable.
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.