Calculate soil swell volume after excavation. Enter bank volume and swell factor to find loose volume for hauling and disposal estimates.
When undisturbed soil is excavated, it loosens and expands in volume. This expansion is called swell, and it's one of the most critical factors in earthwork estimating. The swell factor determines how much more volume you'll have to haul away compared to the volume you measured in the ground.
Different soil types swell different amounts. Sand expands 10–20%, clay 30–40%, and rock can swell 40–70% when broken into fragments. This calculator converts bank (in-place) volume to loose (after-excavation) volume using the swell factor for your specific soil type.
Accurate swell calculations prevent expensive trucking surprises. If you measure 100 cubic yards in the bank and plan trucking for only 100 CY, you'll be 20–40% short on truck capacity when the material swells after excavation.
Precise calculations are essential for meeting regulatory requirements, passing inspections, and ensuring the long-term structural integrity and safety of the completed project. This data-driven approach helps contractors minimize rework, avoid delays caused by material shortages, and deliver projects on time and within the agreed budget.
Swell directly affects your hauling costs. A 30% swell means you need 30% more truck loads than the in-ground volume suggests. This calculator converts bank volume to loose volume so your hauling estimates are accurate from the start. Having precise numbers at hand streamlines project planning discussions with clients, architects, and subcontractors, building trust and reducing costly misunderstandings on the job.
Loose Volume = Bank Volume × Swell Factor Swell Increase = Loose Volume − Bank Volume Swell Percentage = (Swell Factor − 1) × 100
Result: 130 CY loose from 100 CY bank
Excavating 100 cubic yards of clay (swell factor 1.3) produces 130 loose cubic yards for hauling. That's 30 extra cubic yards that need truck capacity. At 16 CY per truck, you need 9 loads instead of 7.
Sand: 1.10–1.20. Gravel: 1.12–1.18. Loam: 1.20–1.30. Clay: 1.30–1.40. Hardpan: 1.40–1.50. Blasted rock: 1.50–1.70. These are typical ranges — actual values depend on moisture, gradation, and site-specific conditions.
Three volume states exist for earthwork: Bank (undisturbed in the ground), Loose (after excavation), and Compacted (after placement and compaction as fill). Each state has a different volume for the same mass of soil. Converting between states requires swell and shrinkage factors.
Use bank volume when measuring the hole to be dug. Use loose volume when estimating trucks needed. Use compacted volume when calculating how much fill material to order. Getting the right conversion factor for each stage prevents costly errors in your earthwork estimate.
The most common error is using bank volume for hauling estimates. This underestimates truck needs by 10–40%. Another mistake is ignoring the difference between loose and compacted volume when reusing material as fill — one cubic yard of cut does not fill exactly one cubic yard of fill requirement.
The swell factor is the ratio of loose (excavated) volume to bank (undisturbed) volume. A factor of 1.3 means soil increases 30% in volume when dug up. It accounts for air entering the loosened material.
In its undisturbed state, soil particles are tightly packed with minimal air voids. Excavation loosens the soil structure, allowing air to fill the spaces between particles. This increases the total volume of the material.
Clay typically has a swell factor of 1.3–1.4, meaning it expands 30–40% when excavated. Wet, heavy clay swells more than dry clay. Always verify with your geotechnical report for site-specific values.
Mostly, yes. When loose soil is placed as fill and compacted, it returns to near its original bank volume. However, it rarely compacts to exactly the bank density, so there's usually a small net volume gain (5–10%).
Swell factors are determined from the soil's in-place density and loose density, measured through laboratory testing. Published tables provide typical values by soil type, but site-specific testing is more accurate.
Swell is the volume increase when soil is excavated (bank to loose). Shrinkage is the volume decrease when loose soil is compacted (loose to compacted). They are opposite processes but not exact inverses due to compaction variations.
Yes, significantly. Hauling is often priced per truck load or per cubic yard. If your swell factors are 30%, you need 30% more trucks than the bank volume suggests. This directly increases your hauling budget.
Bank cubic yards (BCY) measure soil in its undisturbed, in-place condition. Loose cubic yards (LCY) measure the same soil after excavation, when swell has increased its volume. Hauling and disposal use LCY.