Flowable Fill (CDF) Calculator
Estimate flowable fill — controlled density fill (CDF) or controlled low-strength material (CLSM) — for trench backfill with the pipe subtracted, abandoned pipe, or voids.
Flowable Fill (CDF) Calculator — ConcreteNear.com
| Fill volume (exact) | 20.93 yd³ |
| Trucks | 3 · last load 3.25 yd³ |
| Per foot of length | 5.65 ft³ |
Cost estimate U.S. average prices
| Flowable fill, placed 23.25 yd³ × $265.78 | $6,179 |
| Short-load fee (last load 3.25 yd³ < 6 yd³) 1 load × $150.00 | $150.00 |
| Estimated total | $6,329 |
- Flowable fill floats pipe — strap it down or place in lifts.
- Long pipe abandonments may call for cellular (foamed) concrete and vent holes; ask your supplier.
| Inputs | |
| What are you filling? | Trench (around a pipe) |
| Length | 100 ft |
| Trench / void width | 24 in |
| Fill depth | 3 ft |
| Pipe outside diameter (subtracted) | 8 in |
| Extra for waste & over-excavation | 10% |
| Ready-mix truck size | 10 yd³ |
| Short-load minimum | 6 yd³ |
Planning estimate only — confirm with your supplier or contractor.
Prices used — edit any price to match your local quote
| Item | Unit price | Basis & source |
|---|---|---|
| Flowable fill, placed per yd³ | public source Florida DOT Item Average Unit Cost 2025, item 0121 70 Flowable Fill (13 contracts) (2025 lettings) — Small sample of public jobs, placed price. Plant price for delivered CDF is usually lower — ask your supplier. | |
| Short-load fee (per truck under the minimum) per load | starting estimate Starting estimate. Ready-mix producers charge a flat or per-yard fee for small loads; ask your dispatcher. |
How to use this calculator
- Pick trench backfill, pipe abandonment or void fill.
- Enter length, width and depth (and pipe diameters).
- Add extra for irregular trench walls.
- Read yards and trucks.
Formulas
Trench ft³ = length × (width × depth − π × (pipe OD ÷ 2)²)Pipe abandonment ft³ = length × π × (pipe ID ÷ 2)²Order yd³ = ft³ ÷ 27 × (1 + waste %)
Questions
How much flowable fill is in a pipe?
A 12 in inside-diameter pipe holds about 0.785 ft³ per foot — about 1 yd³ per 34 ft.
Is flowable fill the same as concrete?
No. It is a self-leveling, low-strength mix designed to be easy to dig out later; it is not a structural concrete.
Will flowable fill float a pipe?
Yes — it is heavy and fluid. Anchor the pipe or place it in lifts.
Sources & assumptions
Prices checked 2026-11-10. State pricing multiplies national figures by the U.S. Bureau of Economic Analysis regional price parities (goods for materials, services for labor and services). RPPs compare general consumer price levels (U.S. = 100). They are not construction-specific; we use RPP Goods for materials and RPP Services: Other (excludes rents) for labor and services.
- Flowable fill, placed — Florida DOT Item Average Unit Cost 2025, item 0121 70 Flowable Fill (13 contracts) (2025 lettings). Small sample of public jobs, placed price. Plant price for delivered CDF is usually lower — ask your supplier.
Starting estimates No public price series was found for: Short-load fee (per truck under the minimum). These defaults are editable placeholders — replace them with a local quote.
Results are planning estimates, not quotes or engineering advice. Codes, specifications and your supplier's numbers govern.
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