J. Eng. Technol. Sci., Vol. 53, No. 2, 2021, 210206 Received May 19 th , 2020, 1 st Revision August 22 nd , 2020, 2 nd Revision October 8 th , 2020, Accepted for publication November 19 th , 2020. Copyright ©2021 Published by ITB Institute for Research and Community Services, ISSN: 2337-5779, DOI: 10.5614/j.eng.technol.sci.2021.53.2.6 Site Soil Classification Interpretation Based on Standard Penetration Test and Shear Wave Velocity Data Windu Partono 1* , Muhammad Asrurifak 2 , Edy Tonnizam 3 , Frida Kistiani 1 , Undayani Cita Sari 1 & Kukuh Cahya Adi Putra 1 1 Civil Engineering Department, Engineering Faculty, Diponegoro University, Jalan Prof. Soedarto SH., Tembalang, Semarang 50275, Indonesia 2 Faculty of Civil Engineering and Planning, Institut Sains dan Teknologi Nasional, Jalan Moh. Kaffi II, Srenseng Sawah, Jagakarsa, Jakarta Selatan12640, Indonesia 3 Centre of Tropical Geoengineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Baru, Johor, Malaysia *E-mail: windu_bapake_dila@yahoo.com Highlights:  Site soil classification was conducted using the standard penetration test (N-SPT) pressure and shear wave velocity (VS) values.  The VS data were collected from single and array microtremor investigations.  Site soil classification was calculated based on the SNI 1726:2019 seismic code.  N-SPT maximum 120 produced different VS and site soil classification compared to N-SPT maximum 60. Abstract. Site soil classification provides vital information for predicting the soil amplification or the site factor. The site factor is important for calculating the surface spectral acceleration in the seismic design of buildings. Based on the Indonesian seismic code, site soil classification can be conducted by calculating the average standard penetration (N-SPT) resistance, the average shear wave velocity (VS) and the average undrained soil strength (Su) of the upper 30 m of a subsoil layer. Different results may be obtained at the same location when the site soil classification is predicted using N-SPT than when using VS data. The restriction of N-SPT values until a maximum of 60 compared to a VS maximum of 750 m/sec can produce different soil classes and will directly impact the calculation of the surface spectral acceleration. This paper describes the different results of site soil classification prediction calculated using the average N-SPT and the average VS, conducted at Semarang City, Indonesia. Site soil classification maps developed based on both datasets are also presented, to evaluate the different site soil classification distributions. Only soil classes SD and SE were observed using N-SPT maximum 60, whereas soil classes SC, SD and SE were observed using N-SPT maximum 120. Keywords: bedrock; shear wave velocity; site factor; site soil classification; spectral acceleration; standard penetration pressure.