The perceived width, depth, and height of interior spaces depend not only on the actual dimensions of the rooms but also on the brightness of room surfaces and other visual factors. Here, we measured the effect of the acoustic properties of the room surfaces on perceived size. Simulated rectangular rooms (light gray surface textures, no windows) with varying width and depth were presented on an HTC Vive Pro with head-tracking. For each combination of width and depth, one version with reverberant acoustics (mean RT60 = 1.03 s) and one version with damped acoustics (mean RT60 = 0.19 s) were simulated by varying the absorption coefficient of the surfaces. Binaural room impulse responses were generated using the room simulation software RAVEN (https://www.virtualacoustics.org/RAVEN/). 22 participants viewed the rooms on the HMD and listened to speech and sounds of musical instruments inside the simulated space, using dynamic binaural synthesis with head-tracking. Participants estimated room width and depth in units of centimeters. As expected and compatible with previous studies, the estimated width and depth were significantly higher for the reverberant compared to the damped version of the simulated rooms. The mean increase in estimated width and depth was 1.1 % (Cohen’s dz = 0.849) and 1.6 % (dz = 0.854), respectively.