SiteCalculators
  1. Home
  2. Calculators
  3. Variable strip volume

Areas, materials and loads

Variable Width and Depth Strip Calculator

Estimate road, footpath, stone, concrete, drainage or landscaping strip quantities where width, depth or station spacing changes along the work.

Variable Width and Depth Strip Field Report

Average-end-area estimate from entered stations — SiteCalculators

Measured stations

Enter rows in increasing chainage. Add stations wherever the strip geometry changes materially.

Saved locally
Station (m)Width (m)Depth (mm)Side slopeNotesRow actions

Side slope is optional horizontal run per 1 vertical on each side. Enter 0 for a rectangular section.

Material assumptions
%
kg/m³
Editable estimating assumption; verify its loose or compacted basis.
t
Headers: station, width, depth, side_slope, notes.
Drafts and imported CSV data remain in this browser. Nothing is uploaded to SiteCalculators.
Quantity limitation: This is an estimate from representative stations, not a survey volume. Add stations at breaks in width, depth, formation or side slope, and reconcile against approved information and measured site conditions.

How average-end-area strip volume works

Each row describes one cross-section. The entered width is treated as the base or working width. If a side-slope factor is entered, equal slopes are applied to both sides. The calculator averages the cross-sectional areas at adjacent stations and multiplies by their chainage interval.

station area = width × depth + side-slope factor × depth²
segment volume = interval × (start area + end area) ÷ 2
plan area = interval × (start width + end width) ÷ 2

The approach supports irregular station intervals. It does not model curvature or undulations between stations, so spacing must be close enough to represent the actual work.

Worked example

A 25 m strip is measured at chainages 0, 10 and 25 m. Widths change from 2.0 m to 2.5 m and then 3.0 m; depths change from 150 mm to 180 mm and then 200 mm. The two average-end-area segment volumes are added before a 10% allowance and the editable density are applied. Use the worked-example button to inspect every segment.

Using the station table well

  • Measure at every clear change in width, depth or side slope.
  • Keep chainages strictly increasing; use the row buttons to reorder an accidental entry.
  • Use side slope only when its geometry is representative over the interval.
  • Replace the density and vehicle payload examples with supplier and project information.
  • Save a browser-local draft before leaving the page, and export CSV for your field records.

Assumptions and limitations

Widths and depths are interpolated linearly between stations. The plan area uses the entered widths and does not include sloping face area. Allowance is applied to net volume before mass is calculated. Density presets are not supplier-certified, and the result does not establish compaction, specification compliance, formation acceptance or haul legality.

Frequently asked questions

Can the station intervals be different?

Yes. Each segment uses its own chainage difference, so 5 m, 12 m and 20 m intervals can be combined. Use closer intervals where geometry changes quickly.

What does the side-slope factor mean?

A factor of 0.5 means each side moves 0.5 horizontal units for every 1 vertical unit. The added trapezoidal area is factor multiplied by depth squared.

Is this a surveyed earthworks volume?

No. It is a section-based estimate from the values entered. It does not replace a topographical survey, surface model or competent quantity verification.