Excavation Calculator
Calculate excavation step by step: V = D ÷ 6 × (A_bottom + 4·A_mid + A_top) (prismoidal formula).
In short
Formula: V = D ÷ 6 × (A_bottom + 4·A_mid + A_top) (prismoidal formula). Loose = bank × (1 + swell).
What this calculator does
Calculate excavation step by step: V = D ÷ 6 × (A_bottom + 4·A_mid + A_top) (prismoidal formula). Worked example, questions and limitations included.
Use it to turn Base length, Base width, Depth, Side slope (horizontal per 1 vertical), and the other shown inputs into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this construction calculation.
Inputs and what they mean
- Base length
- — number value.
- Base width
- — number value.
- Depth
- — number value.
- Side slope (horizontal per 1 vertical)
- — number value.
- Swell factor
- — Bulking of excavated soil, from soil data.
How to use it
- Enter each value in the unit shown next to the box (use the unit converter first if your numbers are in other units).
- Check the breakdown to see every intermediate step.
- Read the limitations before relying on the result.
Formula
Slope 0 gives vertical sides (a simple box).
Prismoidal formula is exact for a pit with uniform side slopes.
Swell factor is entered from soil data; no soil type is assumed.
V = D ÷ 6 × (A_bottom + 4·A_mid + A_top) (prismoidal formula). Loose = bank × (1 + swell).
Inputs used: Base length, Base width, Depth, Side slope (horizontal per 1 vertical), Swell factor.
Worked example
10 × 5 m pit, 2 m deep, 1:1 slopes
- Top = 14 × 9 = 126 m²; bottom = 50 m²; mid = 12 × 7 = 84 m².
- V = 2/6 × (50 + 336 + 126) = 170.7 m³.
- Loose = 170.7 × 1.25 = 213.3 m³.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Reference price tables
No reference prices are configured. Enter your own prices and rates — this site never assumes them.
Limitations and assumptions
- Level ground, flat bottom, uniform slopes.
- Swell is user-entered.
- Does not assess excavation safety.
- Results are estimates for planning and learning. Real designs, installations and bids must be checked by a qualified, licensed professional against the codes that apply where you work.
- The result depends on the values you enter for this excavation calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
What is swell?
Soil bulks up when dug. Trucks carry loose volume, so haulage is based on bank volume increased by the swell factor.
What side slope is safe?
It depends on soil and local safety rules for trenching and excavation. A competent person must decide; this tool only computes volume.
Is the pit assumed level?
Yes, with a flat bottom and level ground. Check the formula, example, and limitations on this page before using the result for a real construction decision.
How do I use the Excavation Calculator?
Enter the required values for Base length, Base width, Depth, Side slope (horizontal per 1 vertical), Swell factor. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Excavation Calculator use?
V = D ÷ 6 × (A_bottom + 4·A_mid + A_top) (prismoidal formula). Loose = bank × (1 + swell). The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the Excavation Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
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