Fill Dirt Compaction Calculator
Calculate how much loose fill dirt to order to reach a target compacted volume, accounting for the volume lost during compaction.
How this calculator works
Fill dirt arrives loose, but it doesn’t stay that volume once it’s placed and tamped down. This calculator works backward from the compacted volume you actually need to fill, dividing by the expected compaction loss to tell you how much loose material to order.
Formula: Loose volume to order = compacted volume needed ÷ (1 − compaction loss as a decimal). Fill dirt typically loses about 15-25% of its loose volume when compacted in place.
Worked example
20 cubic yards of compacted volume needed, 20% compaction loss:
- Compaction loss as a decimal: 20% = 0.20
- Divisor: 1 − 0.20 = 0.80
- Loose volume to order: 20 ÷ 0.80 = 25.0 cubic yards
Notes
This is why ordering exactly the volume of the hole you’re filling always comes up short. Delivered fill dirt is loose, and it settles and compacts as it’s placed and tamped, so you need noticeably more loose material than the final compacted volume calls for. Sandy soils compact less (a lower loss percentage) than clay-heavy soils, so adjust the compaction loss input to match your material if you know it.
How to use
Enter the compacted volume you need to fill and your expected compaction loss percentage (use 20% if you’re unsure). The calculator divides the compacted volume by the remaining fraction after compaction to tell you how many loose cubic yards to order.
A planning estimate using a typical compaction loss range. Actual compaction varies by soil type and compaction method — order a small margin of extra material regardless.
Frequently asked questions
Why do I need more loose fill dirt than my finished compacted volume?
Loose fill dirt has air pockets between the soil particles. Compacting it — by tamping, rolling, or settling over time — presses those pockets out, shrinking the total volume. Ordering exactly the compacted volume you need leaves you short once it's placed and packed down.
What compaction loss percentage should I use?
Fill dirt typically loses about 15-25% of its loose volume when compacted in place. Sandy soils tend to compact less (lower loss percentage) than clay-heavy soils. If you don't have a specific figure for your material, 20% is a reasonable middle-of-range default.
Does compaction loss vary by soil type?
Yes. Sandy or granular soils generally have less air space to begin with, so they lose a smaller share of their loose volume when compacted. Clay-heavy soils tend to have more air space and can lose more. Adjust the compaction loss input if you know your specific material.
Should I order extra fill dirt beyond this calculated amount?
It's a good idea. This calculator gives a planning estimate based on a typical compaction loss range, but actual compaction depends on soil type, moisture content, and compaction method. A small margin of extra material helps avoid a second delivery if the actual loss runs higher than estimated.
Estimates only. Verify quantities with your supplier before purchasing.