MAXScanner thermal & fluid engineering
Nusselt Number Calculator — Convection, Conductivity & Heat Transfer
Calculate Nusselt number from convective heat-transfer coefficient, characteristic length and fluid conductivity, or recover h from Nu.
Last updated: September 17, 2026
Results
Enter positive L and k; leave exactly one of h or Nu blank
Formula, example and assumptions
Nu=hL/k; h=Nu·k/L.
h=100 W/m²K, L=0.05 m and k=0.6 W/mK gives Nu≈8.33.
- Use a geometry-appropriate characteristic length.
- Fluid conductivity should represent the relevant film/bulk temperature.
Frequently asked questions
What does Nu=1 mean?
It represents heat transfer at the pure-conduction scale; values above one indicate convection enhances transfer.
Is Nusselt number dimensionless?
Yes. The units in hL/k cancel.