Accurate prediction of soil- gas diffusivity (Dp/Do: where Dp and Do are gas diffusion coefficients in soil and free air, respectively) and its variation with soil physical conditions (e.g., soil type/texture, soil density, soil moisture status) are important prerequisites for simulating subsurface gas migration and emission of greenhouse gases across the soil-atmosphere continuum. Literature is abundant with studies using repacked soils for estimating soil-gas diffusivity, however, they are unlikely to mimic realistic conditions in the subsurface, thereby leading to a marked mischaracterization of subsurface gas transport. In this study, measured soil-gas diffusivity in undisturbed soils sampled from differently characterized Danish soil profiles (total of 150 undisturbed soil samples) were used to investigate soil density effects on diffusive gas migration. The selected soils represent a wide range of natural and anthropogenic origins, including agricultural soils, forest soils, urban soils, landfill cover soils, etc. The measurements were within a selected range of matric potentials (−10 to −500 cm H2O) typically representing natural field conditions in subsurface soil. The soils used for this study were subjected to five different density categories (1.0-1.2, 1.2-1.4, 1.4-1.6, 1.6.-1.8, 1.8- 2.0 g cm-3) and showed peak diffusivity within the range of 1.4-1.6 g cm-3 as critical density window at a given suction. A series of predictive and descriptive gas diffusivity models were tested against the measured data for model comparison. Results clearly distinguished the effect of soil structure status due to the accurate performance of SWLR model on measured diffusivity data.