kPa to Litres per Second Calculator

Convert pressure (kPa) to volumetric flow rate (L/s) using pipe diameter and fluid density. Essential for hydraulic engineering and pipe system design.

Hydraulic Flow Calculator:

Uses Bernoulli's principle to convert pressure into flow rate. Supports water, oil, air, and custom fluids.

Pressure to Flow Converter

Fluid Density: 1000 kg/m³ (Water)

System pressure

Internal pipe diameter

Flow Rate Results

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L/s

Enter pressure and diameter

then click "Calculate" for flow rate

kPa to Litres per Second: How Pressure Converts to Flow

Pressure and flow rate are related but measure different things. Pressure is force per unit area, while flow rate tells you how much fluid moves through a pipe each second. Converting between them requires knowing the pipe size and fluid properties.

The Physics Behind It

The conversion happens in two steps. First, pressure becomes velocity using Bernoulli's principle. Then velocity becomes flow rate using the pipe's cross-sectional area.

Step 1: Pressure to Velocity
v = √(2P ÷ ρ)
Where: v = velocity (m/s), P = pressure (Pa), ρ = density (kg/m³)
Step 2: Velocity to Flow Rate
Q = A × v × 1000
Where: Q = flow rate (L/s), A = area (m²), v = velocity (m/s)
Example: 100 kPa through 50mm Pipe
Area = π × (0.025)² = 0.00196 m²
Velocity = √(2 × 100000 ÷ 1000) = 14.14 m/s
Flow = 0.00196 × 14.14 × 1000 = 27.7 L/s

kPa to L/s Conversion Table (Water)

Quick reference for water flow calculations at different pressures and pipe sizes:

Pressure (kPa) Diameter (mm) Flow (L/s)
50 25 4.91
50 50 19.6
100 25 6.94
100 50 27.7
100 75 62.3
150 50 33.9
150 100 135.7
200 50 39.2
200 75 88.2
200 100 156.8
250 50 43.8
250 100 175.3
300 75 108.0
300 150 432.0
400 100 221.7
400 150 498.8
500 100 248.0
500 200 991.8
750 150 683.0
1000 200 1402.5
Why This Matters:

Engineers use this conversion to size pumps, design irrigation systems, and ensure pipes can handle required flow rates. Without accounting for diameter and density, pressure alone tells you nothing about actual fluid movement.