The mechanical properties of short fiber reinforced thermoplastics and their inherent scatter are highly affected by variations in material properties and processing conditions. Usually, this variability is neglected in common deterministic structural simulations and its effect is compensated for by applying higher safety factors. However, this results in oversizing which has a negative impact on the ecological footprint of the components [1]. However, these could potentially be reduced if uncertainties are integrated into future simulation methods. To achieve this aim, the sources of variability must first be identified. Subsequently, the quantified uncertainties need to be propagated through the structural model. This step is typically associated with high computational cost which makes the use of surrogate model indispensable [2]. This work introduces an efficient uncertainty quantification framework for multiscale simulations. The proposed approach is able to effectively quantify the impact of selected uncertain input parameters on the simulation results. To demonstrate the procedure, the effective mechanical properties of a short fiber reinforced polypropylene are predicted using a two-step homogenization method [3]. To accelerate the uncertainty propagation step, a suitable surrogate model is employed in conjunction with an efficient sampling technique. The developed framework offers the capability to efficiently evaluate correlations between the input parameters on the one hand and input-output correlations on the other hand. Additionally, sensitivity analyses can be conducted in a fraction of time required by high-fidelity simulations. [1] F. Wittemann, C. Krauß, and L. Kärger, Efficient Approximation of Varying Fiber Orientation States in Injection Molded Pars Under Consideration of Multiple Manufacturing Uncertainties. Applied Composite Materials, Vol. 32, pp. 149-172, 2025. [2] J. Proy, F. Massa, D. Notta-Cuvier, F. Lauro, T. Tison and G. Spingler. Integrating fibers and injection molding process variability in short-natural-fiber-reinforced thermoplastics behavior: A review. Materials Today Communications, Vol. 29, 102785, 2021. [3] P.A. Hessman, F. Welschinger, K. Hornberger and T. Böhlke. On mean field homogenization schemes for short fiber reinforced composites: Unified formulation, application and benchmark. International Journal of Solids and Structures, Vol. 230-231, 111141, 2021.