Pipe Sizing Calculator

Calculate pipe diameter from flow rate and velocity

Flow Rate & Velocity
⚠️ This calculator is a simple reference (preliminary estimation) tool based on standard engineering formulas. Actual quantities may differ due to site conditions, material types, construction tolerances, and applicable codes. calcstool.com assumes no legal liability for any direct or indirect damages resulting from material orders, designs, or construction based on these calculations.
FAQ
What is the recommended velocity for fire pipes?
Wet sprinkler systems typically use ≤6m/s, dry systems ≤10m/s. Fire hydrant pipes recommend ≤4m/s.
What does the A sizing mean?
A refers to nominal diameter in KS (Korean Standard). 25A ≈ 1 inch, 50A ≈ 2 inches. Actual inner diameter varies by pipe schedule.
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Pipe Sizing Formula

From Q = A × V, we derive d = √(4Q/πV) to calculate inner diameter. The nearest standard pipe size larger than the calculated diameter is recommended.