Plumbing Calculators

Pipe sizing, flow rate, and drain slope calculators.

Plumbing sizing and layout calculations follow the International Plumbing Code (IPC) and Uniform Plumbing Code (UPC). Pipe sizing depends on flow rate, friction loss, and pressure drop over distance — the pipe size calculator handles all three. Water heater sizing uses first hour rating (FHR) rather than tank size alone, because FHR accounts for recovery rate and gives a more accurate picture of peak demand capacity. The drain slope calculator enforces the 1/4-inch-per-foot minimum slope rule from IPC Section 704 to prevent solids from settling and causing clogs.