Controlled low-strength fill estimator

Flowable Fill Calculator

Estimate flowable fill or controlled low-strength material volume from trench length, width, depth, over-excavation, waste, and unit cost. Use it for a first supplier call before verifying mix and site rules.

Units

Trench length (ft)Average trench width (ft)Average fill depth (ft)Over-excavation factor Waste / rounding (%)Cost per yd³ or m³ ($)

Fill volume to order

Measured volume

Truck allowance

Rough cost

Flowable fill specs are job-specific

This is a quantity estimate only. Mix design, removability, compressive strength, utility bedding, lift limits, slurry placement, inspection, and local specifications decide the final order.

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Flowable fill formula

Measured yd³ = length × width × depth ÷ 27

Adjusted volume = measured volume × over-excavation factor

Order volume = adjusted volume × (1 + waste %)

Truck allowance = order volume rounded for supplier planning

Sample takeoff

A 60 ft trench that is 2 ft wide and 3 ft deep is 13.3 yd³ measured. With 1.05 over-excavation and 5% waste, order about 14.7 yd³ of flowable fill.An 18 m trench that is 0.6 m wide and 0.9 m deep is 9.7 m³ measured. With 1.05 over-excavation and 5% waste, order about 10.7 m³ of flowable fill.

Flowable Fill Calculator FAQ

How do I calculate flowable fill volume?+

Multiply trench length by average width and depth, convert to cubic yards or cubic metres, then add over-excavation and waste.Multiply trench length by average width and depth, convert to cubic yards or cubic metres, then add over-excavation and waste.

Is flowable fill the same as concrete?+

No. Flowable fill is usually controlled low-strength material. It flows into voids but has different strength and removability requirements than structural concrete.No. Flowable fill is usually controlled low-strength material. It flows into voids but has different strength and removability requirements than structural concrete.

Should I round to truck quantities?+

Yes. Use the order volume as a planning number, then confirm minimum loads, truck scheduling, and supplier rounding.Yes. Use the order volume as a planning number, then confirm minimum loads, truck scheduling, and supplier rounding.