Enter the length, width, and depth into the calculator to determine the select fill needed. This calculator can also evaluate any of the variables given the others are known.
Select Fill Formula
Select fill is estimated by volume. For a rectangular area, multiply the length by the width and the fill depth. If your dimensions are entered in feet, divide by 27 to convert cubic feet to cubic yards.
V = L \times W \times D
SF = \frac{L \times W \times D}{27}- SF = select fill required in cubic yards
- V = volume in cubic feet
- L = length of the area
- W = width of the area
- D = fill depth
If all dimensions are entered in meters, the direct result is cubic meters:
V_{m^3} = L \times W \times DWhat Is Select Fill?
Select fill is a designated fill material used when a project needs more consistent compaction, grading performance, drainage behavior, or support characteristics than ordinary fill. The exact material can vary by job specification, but the calculator always starts with the same core question: how much volume is needed to fill the space?
How to Calculate Select Fill
- Measure the length and width of the area to be filled.
- Determine the average depth of fill needed.
- Convert all dimensions to the same unit before calculating.
- Multiply length, width, and depth to get volume.
- Convert the result to the unit you plan to order, most commonly cubic yards.
For areas with changing depth, use the average depth or break the site into smaller sections and add the results together.
SF_{total} = SF_1 + SF_2 + \cdots + SF_nQuick Depth Conversions
Many fill depths are measured in inches while the site dimensions are measured in feet. Converting depth correctly prevents major ordering errors.
| Depth | Feet |
|---|---|
| 1 in | 0.0833 ft |
| 2 in | 0.1667 ft |
| 3 in | 0.25 ft |
| 4 in | 0.3333 ft |
| 6 in | 0.5 ft |
| 8 in | 0.6667 ft |
| 12 in | 1 ft |
Example
If an area is 24 feet long, 18 feet wide, and needs 6 inches of select fill, convert 6 inches to 0.5 feet and substitute into the formula.
SF = \frac{24 \times 18 \times 0.5}{27} = 8The required select fill is 8 cubic yards.
Ordering Considerations
The calculator gives the finished geometric volume. In the field, the amount ordered may be slightly higher if you need to account for compaction, grading loss, uneven subgrade, or material handling. A simple ordering adjustment can be expressed as:
Q_{order} = SF \times (1 + a)- Qorder = estimated quantity to order
- SF = calculated fill volume
- a = allowance for compaction, waste, or site variation
If your supplier sells in whole or half-yard increments, it is usually practical to round up rather than down.
Tips for Better Accuracy
- Use average depth only when the grade changes gradually.
- For irregular spaces, split the area into rectangles and calculate each one separately.
- Keep all measurements in the same unit system before solving.
- Measure after rough grading whenever possible to reduce overestimation.
- Confirm whether the quantity needed is based on loose fill or compacted in-place fill.
Common Questions
Why do you divide by 27?
There are 27 cubic feet in 1 cubic yard, so dividing cubic feet by 27 converts the result to cubic yards.
What if the area is not a perfect rectangle?
Break the space into smaller rectangles, calculate each section, and add them together.
Should depth be measured in the center or at the edges?
Measure depth at several points and use the average when the thickness varies across the area.
Can this calculator be used for pads, trenches, and grading areas?
Yes, as long as the filled space can be represented as one or more rectangular volumes.
