This article describes the IH SkinPerm mathematical tool for estimating dermal absorption. The first part provides the scientific background of the IH SkinPerm model, including the QSARs and the developed differential equations. Then the practical value of the tool is demonstrated through example dermal absorption assessments for substances with skin notations. IH SkinPerm simulates three types of dermal absorption scenarios relevant to occupational environments. The first is dermal absorption from instantaneous splash type exposures onto bare skin for pure liquids. The second estimates dermal absorption from the deposition of pure liquids over time. The third enables estimation of dermal uptake from an airborne vapor concentration. A simulation with IH SkinPerm was made using vapor absorption data published from volunteer exposure studies. Comparison of measured and estimated dermal absorbed dose showed IH SkinPerm estimated dermal absorbed dose was within a factor of 3 compared to the reported study values. IH SkinPerm accounts for substance volatility and evaporated mass and provides real-time description of dermal absorption with graphical displays and numerical outputs. To assess absorption resulting from dermal exposure scenarios, the mass of the substance loaded onto the skin, substance physical chemical properties, exposure duration, and the skin surface area affected are the only required input parameters.