Poiseuille's Law Calculator
Q = π r⁴ ΔP / (8 μ L) for laminar, incompressible, steady flow.
How to Use This Calculator
1
Enter ΔP, r, L, μ
Use SI units. Ensure laminar flow assumptions are valid (Re < 2300).
2
Calculate Q
Result is volumetric flow rate in m³/s.
Formula
Q = π r⁴ ΔP / (8 μ L)
Where: r radius, L length, μ viscosity.
Example: ΔP=5000 Pa, r=3 mm, L=1 m, μ=0.001 Pa·s ⇒ Q≈ 1.59e−5 m³/s.
Frequently Asked Questions
Does it apply to turbulent flow?
No. Poiseuille's law is for laminar, fully developed, incompressible, Newtonian fluids in circular tubes.
What if I have diameter?
Use r = D/2. Keep units consistent.