Breakwater Toe Volume Calculator

• Bulk volume: V = A × L
• Rectangular area: A = W × H
• Trapezoid area: A = H × (B + T) ÷ 2
• Slope-based top width: T = B + 2 × S × H (S = H:1V)
• Triangular area: A = 0.5 × Base × H
• Overbuild: V_adj = V × (1 + Overbuild/100)
• Equivalent solid volume: V_solid = V_adj × (1 − Porosity/100)

Use bulk volume for placement quantities. Use equivalent solid volume when comparing with solid material content or quarry estimates.

1. Select your unit system, then choose the toe cross-section shape.
2. Enter the toe length along the breakwater or revetment alignment.
3. Provide the required geometry fields for the chosen shape.
4. Add overbuild to cover placement tolerance and construction variability.
5. Set porosity to reflect rock voids in placed material.
6. Optionally enable mass estimation and enter an appropriate bulk density.
7. Press Submit to view results above the form, then export CSV or PDF.

Toe protection role in coastal stability

The toe berm helps resist scour, sliding, and undermining at the seaward edge of armor layers. A reliable quantity estimate supports early budgeting, quarry scheduling, and barge or truck planning. This calculator converts basic section geometry and toe length into bulk placement volume that can be compared across alternatives.

Cross-section geometry drives quantities

Toe volumes are often dominated by section width and thickness rather than alignment length alone. Rectangular sections are common for simple bedding or filter layers, while trapezoids represent placed rock profiles with side slopes. When drawings provide an area directly, the custom-area option avoids double entry and reduces transcription mistakes.

Overbuild allowance and construction tolerance

Field placement rarely matches neat lines. Overbuild is used to cover irregular rock packing, settlement, minor over-excavation, and profile trimming. Project teams may evaluate several allowances (for example, 3–12%) and then align the selected value with method statements, survey control, and expected rehandling.

Porosity and solid content interpretation

Bulk volume represents the occupied space in the water or on the seabed, including voids between stones. Porosity commonly varies with grading, placement method, and layer thickness. Using the porosity input, the tool also reports an equivalent solid volume that is useful when comparing with solid material supply assumptions.

Linking volume to logistics and procurement

When bulk density is provided, the calculator estimates mass to support transport planning and stockpile sizing. In metric mode, mass is reported in tonnes using t/m³; in imperial mode, the conversion uses tons per cubic yard. For tendering, record the selected inputs, export the CSV or PDF, and keep them with the calculation register for traceability. Review units carefully, especially when mixing survey feet and metric drawings. Small unit mismatches can create large ordering errors on long structures.

1) What volume should I use for ordering rock?

Use the adjusted bulk volume for placed quantities because it includes overbuild. Confirm whether the contract measures in-place volume, delivered volume, or mass, and align the input assumptions with that measurement basis.

2) How do I choose the cross-section shape?

Select the option that matches the drawings. Rectangular suits uniform layers, trapezoid suits sloped profiles, triangular suits wedge details, and custom area suits sections where the design area is already computed from CAD.

3) Why does the tool show an equivalent solid volume?

Placed rock contains voids. Equivalent solid volume removes the void fraction using porosity, helping you compare against solid material assumptions or check sensitivity when grading or placement methods change.

4) What porosity value is reasonable?

Porosity depends on grading and placement. Use project data when available, then run a range to see sensitivity. If unsure, start with a mid-range value and revise after trials or as-built surveys.

5) What does overbuild represent?

Overbuild accounts for placement tolerance, uneven seabed, settlement, and profile trimming. It is not a design safety factor; it is a quantity allowance. Choose it based on construction method and survey controls.

6) How is mass estimated in imperial units?

The tool converts adjusted bulk volume from ft³ to yd³ by dividing by 27, then multiplies by density in ton/yd³. Check whether your supplier uses short tons or metric tonnes and stay consistent.

7) Can I export my inputs with the results?

Yes. After calculation, downloads include key inputs, computed area, bulk volume, overbuild, porosity outputs, and optional mass. Save exported files with your drawing reference and calculation date for auditability.