Excavation Calculator
This excavation calculator works out the volume of soil to dig and the loose spoil it produces. Enter the length, width, and depth and the excavation calculator returns the dig volume in cubic meters and cubic yards, plus the bulked-up soil to cart away. It works as a dirt excavation calculator, a soil excavation calculator, and a trenching calculator.
Results
The Excavation Calculator is part of our Surveying collection. Browse more surveying to size, convert, and check your work alongside this tool.
What the excavation calculator does
The excavation calculator gives you two numbers that matter on site: the volume you dig, and the larger volume of loose spoil that comes out. Soil swells when dug, so this soil excavation calculator applies a bulking factor to tell you how many truckloads you will really cart away. As a trenching calculator and dirt excavation calculator it handles trenches, footings, and open digs alike.
Excavation volume formula
The excavation calculator multiplies the three dimensions, then adds bulking for the spoil:
The bulking term is why the excavation volume you remove is larger than the hole you leave. For a trench, the same trench volume calculator formula applies using the trench length, width, and depth.
Excavation calculator example
A trench 5 m long, 3 m wide, and 1.5 m deep gives a dig volume of 22.5 cubic meters. With 25 percent bulking, the excavation calculation puts the loose spoil at about 28.1 cubic meters, or roughly 36.7 cubic yards for the truck.
How to use the excavation calculator
Enter the length, width, and depth of the dig in meters, plus a bulking factor. Around 25 percent suits most soils. The excavation calculator reports the in-ground dig volume and the loose spoil volume, and the excavation calculator cubic yard output helps if your trucks are measured that way.
Reading the excavation calculator result
Use the dig volume to plan the hole and any backfill or concrete that replaces the soil. Use the larger spoil volume from the soil excavation calculator to book skips or trucks, because loose soil takes more space than it did in the ground. The excavation calculator cubic yard figure matches how most haulers price a load.
When to use the excavation calculator
- Working out spoil removal for foundations with the excavation calculator
- Sizing a dig with the trenching calculator or trench volume calculator
- Estimating footing digs with the footing excavation calculator
- Booking trucks from the excavation calculator cubic yard result
Common excavation calculation mistakes
- Booking trucks on dig volume. Loose spoil is larger; use the bulked figure.
- One bulking factor for all soils. Clay swells far more than gravel.
- Forgetting backfill. Some spoil may go back, changing what you cart away.
Tips for accurate excavation results
- Match the bulking factor to the soil type for an accurate excavation calculation.
- Book removal on the spoil volume, not the dig volume.
- Use the excavation calculator cubic yard figure to match hauler pricing.
Why the excavation calculator separates dig from spoil
The gap between the hole you dig and the pile you remove trips up a lot of estimates, and the excavation calculator exists to close it. Undisturbed ground is compacted; the moment you break it up, air fills the gaps between the loosened material and the volume grows. That is bulking, and it means the spoil from an excavation calculation is always larger than the neat geometric volume of the hole. Book skips on the hole size and you will run short.
Bulking factors and soil type
How much soil swells depends on what it is, which is why the soil excavation calculator lets you set the bulking factor. Sand and gravel barely change, around ten to fifteen percent. Common soil sits near twenty-five. Heavy clay can swell by forty percent because it breaks into chunky clods with big voids. Choosing a factor that matches the ground is what turns the dirt excavation calculator from a rough guess into a number you can order trucks against, and the excavation calculator cubic yard output makes that order straightforward.
Soil bulking factor chart
Typical bulking used in the calculation of loose spoil:
| Soil type | Bulking factor |
|---|---|
| Sand / gravel | 10–15% |
| Common soil | 20–30% |
| Clay | 30–40% |
Excavation Calculator FAQ
How do I calculate excavation volume?
Multiply length by width by depth for the dig volume. The excavation volume calculator then adds a bulking factor to give the loose spoil you remove, in cubic meters or cubic yards.
What is a bulking factor?
Soil swells when dug, so it takes more space loose than in the ground. The soil excavation calculator uses a bulking factor, around 25 percent for common soil, to size the spoil.
How do I calculate a trench?
Use the trench length, width, and depth in the trenching calculator. The trench volume calculator multiplies them and adds bulking, the same as any excavation.
Which volume do I use to book trucks?
Use the loose spoil figure, not the dig volume, because trucks carry the bulked-up soil. The excavation calculator cubic yard output matches how haulers price it.