How to use it
- Enter the Length and Width of the excavation in metres.
- Enter the Depth in metres, measured from the starting level to the formation level.
- Set Wastage (%) for over-dig, working space and swell. The default is 5%.
- Read Base Volume (the exact in-ground volume) and Total Volume (with the allowance). Use the Total Volume for trucks and disposal.
The formula
Base volume = length × width × depth. Total volume = base volume × (1 + wastage ÷ 100). With dimensions in metres the result is in cubic metres (m³).
What changes the result
This is a box calculation, so it assumes vertical sides and a flat bottom. Sloped sides, benching and working space around foundations add volume: use the average length and width of the excavation, or add them to the dimensions. Excavated soil also swells (bulks) once loosened, so it fills more truck volume than it took up in the ground; raise the percentage to cover that when sizing haulage.
Earthwork practice on UAE sites
Volumes are normally measured in the ground (bank cubic metres) for payment and in loose volume for trucking, so be clear which one the number is for. Excavation near services, a high water table or sabkha ground in coastal areas can change the method and the quantity, and the site investigation report is the place to check. Plan the excavator, the dump trucks and the disposal route together.
Worked examples
- A 20 m × 8 m pit dug 2 m deep is 320 m³ in the ground; allow 336 m³ for trucking and disposal.
- A 100 m pipe trench, 1.2 m wide and 1.5 m deep: 180 m³ base, 189 m³ with the allowance.
- A 30 m × 20 m basement 4 m deep with 10% for swell and over-dig: 2,640 m³ to haul away.
Excavation volume by depth (20 m × 8 m)
Printable chart| Depth (m) | In the ground (m³) | With 5% allowance (m³) |
|---|---|---|
| 0.5 | 80 m³ | 84 m³ |
| 1 | 160 m³ | 168 m³ |
| 1.5 | 240 m³ | 252 m³ |
| 2 | 320 m³ | 336 m³ |
| 2.5 | 400 m³ | 420 m³ |
| 3 | 480 m³ | 504 m³ |
| 4 | 640 m³ | 672 m³ |
| 5 | 800 m³ | 840 m³ |
A 20 m × 8 m excavation with a 5% allowance. For another footprint, enter your own length and width above.
Frequently asked questions
How do I calculate excavation volume?
Multiply length × width × depth in metres. For sloped sides use the average length and width at mid-depth.
How do I calculate the volume of a trench?
Use the trench length, width and depth in the calculator above. Add the allowance for over-dig and swell.
What is bulking or swell in excavation?
Soil takes up more space once it is dug than it did in the ground. Raise the Wastage (%) to size trucks and disposal for the loose volume.
Does the calculator handle sloped sides?
No, it assumes straight sides. Use the average dimensions of the excavation, or split it into sections.
How many truckloads is my excavation?
Divide the Total Volume by the capacity of your truck in cubic metres, and round up. Check the truck capacity with the supplier.
Equipment for this job
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