Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Fluid Mechanics - Imperial and SI Units vs. Dimensions

Imperial (USCS) and SI dimensions and units terminology in fluid mechanics.

Fluid mechanics in the

  • Imperial or USCS - United States Customary Units
  • International System of Units - SI system
Fluid Mechanics - Imperial and SI Units vs. Dimensions
TerminologyDimensionsImperial Units
Acceleration due to gravity L / T2 ft/s2 m/s2
Area L2 ft2 m2
Chezy roughness coefficient L1/2 / T ft1/2/s m1/2/s
Critical Depth L ft m
Density F T2/ L4 lb s2/ ft4
N s2/m4
Depth L ft m
Depth in open channel L ft m
Diameter L ft m
Distance from solid boundary L ft m
Flow rate L3 / T ft3/s m3/s
Force F lb N
Force due to pressure F lb N
Hazen Williams roughness coefficient L0.37 / T ft0.37/s m0.37/s
Head loss due to friction L ft m
Head of height L ft m
Head of weir L ft m
Height above datum L ft m
Hydraulic radius L ft m
Kinematic viscosity L2/ T ft2/s m2/s
Length L ft m
Manning's roughness coefficient T / L1/3 s/ft1/3 s/m1/3
Mass F T2/ L lb s2/ft N s2/m
Modulus of elasticity F / L2 lb/in2 (psi) Pa
Perimeter, Weir Height L ft m
Pressure F / L2 lb/ft2 Pa
Radius L ft m
Shear stress F / L2 lb/ft2 Pa
Size of roughness L ft m
Specific weight F / L3 lb/ft3 kg/m3
Surface tension F / L lb/ft kg/m
Time T s s
Thickness L ft m
Time T s s
Total head L ft m
Unit flow rate L3 / T L ft3/(s ft) m3/(s ft)
Velocity L / T ft/s m/s
Viscosity F T / L2 lb s/ft Pa s
Weight F lbf N
  • L - length
  • F - force
  • T - time

Related Topics

  • Fluid Mechanics

    The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.

Related Documents


Search is the most efficient way to navigate the Engineering ToolBox.

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about

We use a third-party to provide monetization technologies for our site. You can review their privacy and cookie policy here.

You can change your privacy settings by clicking the following button: .


This page can be cited as

  • The Engineering ToolBox (2005). Fluid Mechanics - Imperial and SI Units vs. Dimensions. [online] Available at: [Accessed Day Month Year].

Modify the access date according your visit.

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter