Pipe Sizer - Water Pipe Sizing

Size water pipes in seconds for pressure or gravity systems. Set max friction & velocity, choose material, and get the recommended diameter (SI + IP).

PipeSizer helps you quickly choose the right pipe diameter for water systems — for both pressure and gravity flow.

PRESSURE PIPE SIZING • Size pipes from a target flow rate. • Set your maximum friction rate and velocity limits. • Calculations based on the Hazen-Williams equation.

GRAVITY PIPE SIZING • Size pipes from a target flow rate. • Evaluate flow capacity and velocity under gravity conditions. • Calculations based on the Manning equation.

KEY FEATURES • Automatic recommended pipe size based on your limits. • Multiple pipe materials with built-in coefficients (more added over time). • Works in both SI and Imperial (I-P) units. • Designed for engineers, plumbers, and irrigation/drainage design workflows.

Feedback is welcome — it directly shapes upcoming updates.