A three-dimensional model for gray scale texture in ultrasound B-mode images has been extended to enable absolute quantitative predictions of echo signal levels and texture characteristics. The quantitative aspects of the model are tested with a phantom in which the ultrasonic scattering properties as well as the ultrasonic attenuation coefficient and the speed of sound are known as functions of frequency. Good agreement between theoretical predictions and experimental results was found in the overall brightness of B-mode images, in pixel value histograms, and in an autocorrelation function analysis of images. Passing quantitative tests is additional evidence that the model is a reliable tool for computer simulations involving many important facets of ultrasound B-mode imaging and tissue characterization.