Space Marines are generally described as being about 7 to 7.5 feet tall without their armor. When in full power armor, they can be approximately 8 feet tall. Primaris Space Marines, a newer category, tend to be taller, around 8.5 to 9 feet. These heights are somewhat variable depending on the source, but 7-8 feet is a common accepted range for regular Space Marines, and Primaris Marines stand taller than them at around 8.5 to 9 feet.