Free Water Pipe Size calculator with clear step-by-step results.
Sizes a pipe by solving the continuity equation for diameter at a maximum design velocity, then rounds up to the next standard size and reports the actual velocity that results. The head loss budget shows how much friction the run can afford once static lift is deducted from supply pressure.
Minimum bore
Diameter = 2 x square root of (flow / (velocity x pi))
Head budget
Available head = supply bar x 10.2 - static lift, divided by run length
Pipe sizing, materials, backflow prevention and pressure limits are governed by plumbing and water regulations that vary by jurisdiction. Have designs checked by a qualified plumber or engineer.
Above that, flow noise becomes audible, erosion-corrosion accelerates in copper, and water hammer forces on valve closure rise with the square of velocity.
Yes, for water at ordinary temperatures - one bar lifts a water column about 10.2 metres. That conversion is what links pressure and head in pipe sizing.