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Both calculators run independently — change the inputs on either side to compare results.

Pipe Flow Calculator

Determine pressure drop in circular pipes using the Darcy-Weisbach equation. Use this when designing water supply lines, HVAC ducts, or industrial piping systems to ensure adequate flow.

Pipe Diameter (m)

Pipe Length (m)

Pipe Material

Flow Velocity (m/s)

Kinematic Viscosity (m²/s)

Fill in the required fields to see your result.

Fluid Mechanics

Weir Flow Calculator

Calculate the volumetric flow rate of water passing over a weir based on weir width, upstream head, and weir type. Used by civil engineers and hydrologists to measure or control open-channel flow in rivers, canals, and water treatment plants.

Weir Width (m)

Head Above Weir (m)

Discharge Coefficient

Fill in the required fields to see your result.

Key differences

	Pipe Flow Calculator	Weir Flow Calculator
Category	Fluid Mechanics	Fluid Mechanics
Inputs required	5	3
Result	Pressure Drop (Pa)	Flow Rate (m³/s)
What it does	Determine pressure drop in circular pipes using the Darcy-Weisbach equation. Use this when designing water supply lines, HVAC ducts, or industrial piping systems to ensure adequate flow.	Calculate the volumetric flow rate of water passing over a weir based on weir width, upstream head, and weir type. Used by civil engineers and hydrologists to measure or control open-channel flow in rivers, canals, and water treatment plants.