The purpose of this research is to analyze the understanding and consistency of physics concepts of high school students on temperature and heat material. This research uses descriptive quantitative research. The population and sample in this study used 12th-grade high school students in Malang in the even semester of the 2023/2024 school year with 33 students. Then the data collection technique here uses a multi-tiered E-diagnostic test. The multi-tier test consists of five levels of instruments with multiple choice questions to determine understanding and see the consistency of student concepts. The number of multi-tier tests used was 15 items on temperature and heat material. The results of the analysis show that students' understanding is in the low category while concept consistency produces a logit person reliability value in the statistical table of 0.03 based on Winstep analysis. It can be understood that both students' understanding and concept consistency are in the very low category of temperature and heat.