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🚰 Tool

Pipe Size Calculator

Enter a peak flow rate and a target velocity to estimate the internal pipe diameter and nearest nominal size (DN). It uses the continuity equation for a planning-level result.

Typical 1–2 m/s for supply pipe

Result

Required internal diameter–
Nearest nominal size–

Planning estimate from the continuity equation (area = flow ÷ velocity) — confirm the final design with a qualified engineer and local code.

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FAQ

How is pipe size calculated?
From the continuity equation: diameter is derived from the flow rate and a chosen velocity (area = flow ÷ velocity). Keeping velocity around 1–2 m/s limits noise and erosion; confirm against the fixture-unit method and local code.
What velocity should I use?
For residential water supply, roughly 1–2 m/s is common — lower for quiet systems, higher to save material. This tool defaults to 1.5 m/s; the final size should be checked against pressure-drop limits.

Need the materials supplied?

Turn your figures into a coordinated MEP package — send your project for a quote.

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