Weber Number Calculator

About this calculator

The Weber number (We) is a dimensionless quantity that compares a fluid’s inertial force to its surface tension force: We = ρv²L / σ, where ρ is fluid density, v is velocity, L is a characteristic length (such as droplet diameter), and σ is surface tension. A low Weber number means surface tension dominates and holds a droplet together; a high Weber number means inertia wins and the droplet is likely to deform or break apart.

Fluid dynamics engineers rely on the Weber number to predict droplet and bubble breakup, which matters directly for inkjet printing (getting consistent droplet formation), spray atomization in combustion and agricultural sprayers, and coating processes where a liquid film must stay uniform. This calculator takes your density, velocity, characteristic length, and surface tension and returns the Weber number.