Model conductivity from heat flux tests or mixtures. Switch methods, check units, and view diagnostics. Download clean tables for audits, labs, and clients quickly.
| Soil type | Porosity n | Saturation Sr | Bulk density ρb (kg/m³) | Estimated k (W/m·K) |
|---|---|---|---|---|
| Dry sand | 0.40 | 0.10 | 1550 | 0.25 – 0.35 |
| Moist loam | 0.45 | 0.55 | 1450 | 0.80 – 1.30 |
| Wet clay | 0.50 | 0.85 | 1350 | 1.20 – 1.90 |
| Gravelly soil | 0.30 | 0.60 | 1800 | 1.40 – 2.40 |
Soil thermal conductivity (k) describes how quickly heat moves through soil. This tool supports three paths: a steady lab-style calculation from measured heat rate, an engineering estimate based on soil state, and a calibrated moisture model. Results are reported in W/(m·K).
Conductivity controls ground heat exchange for buried pipes, shallow foundations, geothermal loops, and seasonal frost behavior. Higher k generally increases heat transfer rates, which can improve thermal response but may also raise heat losses. For energy models, conductivity interacts with density and heat capacity to shape temperature transients.
Dry, loose soils often fall near 0.2–0.6 W/(m·K), while moist mineral soils commonly rise to 0.8–1.5 W/(m·K). Dense, saturated sands and gravels may exceed 2.0 W/(m·K). Highly organic soils can remain comparatively low, sometimes near 0.1–0.5 W/(m·K) when dry.
Air-filled pores are strong insulators, so dry soil tends to have low conductivity. As water replaces air, heat transfer improves because liquid water conducts far better than air. Porosity sets the pore volume available, while saturation (Sr) indicates how much of that pore space is water-filled.
Use Fourier conduction when you have a controlled setup with measured heat rate, thickness, area, and temperature difference. Use the Johansen-style estimate when you know porosity, bulk density, and saturation. Use the empirical moisture model when you have site-specific calibration coefficients.
In the soil-state estimate, the tool reports dry conductivity (kdry), saturated conductivity (ksat), and the Kersten number (Ke). Ke blends between dry and saturated limits and is constrained to 0–1 for stable results. If ksat is close to kdry, moisture effects are minimal.
Keep units consistent, especially thickness (m) and area (m²). For lab tests, ensure steady conditions before recording Q and ΔT. For field estimates, porosity typically ranges 0.25–0.60 and bulk density often ranges 1200–2000 kg/m³, depending on compaction and texture.
Use the export buttons to capture assumptions with outputs. For engineering notes, record method choice, moisture state, and any default conductivities you adjusted. When comparing scenarios, run multiple saturation values (for example 0.2, 0.5, 0.8) to bracket expected performance.
This calculator reports conductivity in W/(m·K). That unit is standard in heat transfer and is convenient for soil and building-energy calculations.
Water conducts heat far better than air. As saturation rises, air-filled pores shrink, so heat can flow through a more continuous water–solid network.
Use Fourier conduction for measured heat-rate tests. Use the soil-state estimate when you know porosity, bulk density, and saturation. Use the empirical model when you have calibrated coefficients for your site.
Ke is a moisture-dependent factor that blends dry and saturated conductivity. It increases with saturation and is constrained between 0 and 1 for stability.
Defaults are typical near room temperature, but real values vary with temperature, salinity, and mineralogy. Adjust them if you have better references or lab measurements.
Yes. A negative ΔT indicates heat-flow direction. The magnitude of k is what you typically report for material conductivity.
Not directly. Frozen soils have different effective conductivities because ice replaces water and changes pore structure. For frozen conditions, use models specifically developed for ice–water mixtures.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.