A method and system for determination of dimension related information such as volumetric flow rate(s) of a fluid flowing through a channel. In one implementation, the method and system analyzes temporal changes in a moving fluid's velocity profile to calculate the fluid channel dimensions. In turn, the fluid channel dimensions and the fluid velocity profile data may be combined to calculate the volumetric flow rate of the fluid flowing through the channel. In this regard, the geometry of the channel can be characterized using dimensionless variables that relate dimensions, such as the radius across a circular cross-section, to the largest extent of a dimension. For example, in the case where the channel is a cylindrical tube and a pressure gradient is applied long enough for the fluid to have reached a steady state, the dimensionless radius will be the radius at any point divided by the overall radius of the tube. One or more dimensionless variables can be used to characterize geometries: for instance, one dimensionless radius characterizes a circular tube and two dimensionless terms characterize an elliptical tube (one for the major axis and one for the minor axis). The time required for velocity profiles to change from one shape to another may be characterized by dimensionless time. Dimensionless time, in turn, uses the fluid's viscosity and density along with time and overall channel dimensions and may be used in combination with at least one velocity profile to calculate the volumetric flow rate of the fluid flowing through the channel.