The paper presents an investigation on tightening torque and preload prediction for bolts embedded in softwood using steel washers. A basis for the research was a lack of any information on the tightening torque value for bolted connections in the timber structures’ design codes. For this reason, two experimental tests, theoretical analysis and Finite Element modelling, were performed in the paper. The first experiment based on finding the tightening torque to relative displacement relationship. The next one enabled the author to check the maximal compressing force determined by theoretical approach. In this test, dependencies between plastic modulus including material’s compaction and modulus of elasticity were found too and then applied to the numerical model. Tightening torque was calculated according to agreed formulas elaborated for steel structures based on the obtained preload force value. The high correlation between results from the prepared numerical models and experimental tests was observed. The research presented in the paper has multiple applications, as estimating a proper tightening torque value that should clamp a bolted connection, predicting stresses in connection’s components and clamping pressure when connecting several elements due to tightening torque and bolt preload force introduction or predicting the structural response of multiple bolts connections in the first phase of the loading.