Tools • Free Calculator
Trench Calculator with live bedding zones
Draws your trench as you type — enter bottom width, depth, and pipe size and the cross-section redraws to scale, so the pipe is always in proportion to the trench around it. Color-coded bedding, pipe zone, backfill, and pavement layers with bank CY, swelled CY, haul-off, and import tons sized to each material's unit weight. Built for heavy civil, commercial sitework, and utility bidding.
BidSync AI — Trench Calculator
Live utility-trench cross-section, drawn to scale. Bottom width defaults to 2.5 ft — change it and the trench walls move out to match, with the pipe always in proportion. Bedding zones, pipe zone, backfill, haul-off, and import tons sized by the unit weight of each material you select.
| Section (color key) | In-Place CY | CY w/ Swell | Tons | |
|---|---|---|---|---|
| Bank ExcavationNative Soil | — | — | — | |
| Bedding Below Pipe— | — | — | — | |
| Pipe Zone (auto-sized)— | — | — | — | |
| Final Backfill— | — | — | — | |
| Base Course— | — | — | — | |
| Asphalt Paving— | — | — | — |
Enter dimensions to begin.
Need trench & pipe quantities from plans automatically?
BidSync AI extracts spans, sizes, and bedding classes from PDF plan sets — auto-scoped to municipal standard details.
Formulas: Bank = trapezoidal avg-width × depth × length ÷ 27. Loose = In-place × (1 + Swell%). Spoil reuse: native backfill needs In-place ÷ (1 − Shrink%). Pipe zone = bedding + OD + cover band, minus pipe & bedding solids. Tons = CY × selected unit weight. For automated trench & utility takeoffs from plan sets, see Earthwork Takeoff →
Want it embedded? Copy this widget to your blog: <TrenchCalculator /> — or embed as iframe from bidsyncai.com/tools/trench-calculator.
Why estimators start here
Live cross-section: the trench redraws on every keystroke, so bedding, pipe zone, and cover mistakes are visible before they hit the bid. Quantities and profile can't disagree — the colors match the totals.
Formula transparency
Avg-width × depth × length ÷ 27 = BCY • Loose CY × (1+swell) • Native backfill ÷ (1−shrink) for reuse • Tons CY × t/CY.
Need trench quantities from plans?
BidSync AI reads utility plan sets — pipe runs, sizes, and classes — and auto-applies standard details. No re-keying between the calculator and your bid.
See Earthwork Takeoff →Book 5-Min Demo →How to use
- Enter length and depth — bottom width defaults to 2.5 ft and the profile draws to scale; enter your own bottom width and the trench walls move out to match.
- Pick the pipe size — the pipe is drawn at the same scale as the trench, so you can see the pipe-to-trench ratio.
- Set bedding below and cover above the pipe; the pipe-zone band and volumes calculate automatically.
- Apply your jurisdiction's swell % and shrink %.
- Choose reuse spoil vs 100% import backfill, and pick each zone's material for unit-weight tons.
- Toggle pavement cut & replacement for AC + base quantities when restoring surface.
- Read total bank excavation, haul-off CY, import CY, and import tons — color-keyed to the profile.
FAQ — Trench Calculator
How is the pipe zone material auto-sized?
The pipe zone spans bedding below the pipe, the pipe OD, and the required cover above it. Its footprint uses the trench width at that depth (trapezoidal if sloped), then subtracts the bedding solid and the pipe solid so you never double-order material.
When should I use 100% import backfill?
When the excavated spoil is unsuitable (wet clay, contaminated, unsuitable per spec) or there's no room to stockpile. The calculator then hauls everything off and imports the full backfill — the expansivity ratio shows how much more than bank volume you must source because of compaction loss.
How do I convert import CY to tons for ordering?
Each zone has a material dropdown with its unit weight (t/CY). Tons = CY × unit weight. Order the loose CY and the tons column together — e.g., crushed stone bedding at 1.30 t/CY.
Does this handle MAG 702-style specs?
The calculator doesn't hard-code a jurisdiction, but the standard 6″ bedding + 12″ cover defaults match common municipal standard details (e.g., MAG 702). Adjust to your local spec and the profile redraws.
Automate the whole trench from the plan set
Hand-calculating every pipe run burns hours. Upload vector PDFs or DWGs — computer vision extracts trench lengths, pipe sizes, and classes with evidence for every number.
Related: Earthwork Takeoff · Earthwork Calculator