Stokes Law Calculator

Stokes' Law Calculator is the fastest, most accurate way to solve fluid dynamics problems on iPhone and iPad. Built for engineers, physicists, chemists, geologists, and students, it combines a polished scientific interface with a powerful calculation engine — and it works completely offline. Solve Stokes' Drag Force, Terminal Velocity, and Reynolds Number in seconds. Pick which variable to solve for and the app rearranges the formula automatically: F = 6πμrv, Vt = 2r²Δρg/9μ, Re = ρvD/μ. Every input has its own unit dropdown, so you can work in SI or imperial units without converting by hand. All math runs in SI internally for maximum precision, then results display in your preferred unit. KEY FEATURES • Stokes' Law — solve for drag force, viscosity, radius, or velocity • Terminal Velocity — solve for Vt, radius, or viscosity with overridable gravity (Earth, Moon, Mars) • Reynolds Number — instant validity badge tells you when Stokes' Law applies • Geometry & Mass — sphere volume, surface area, particle mass, settling time, density difference • Built-in Fluid & Material Database — Water, Air, Glycerin, Honey, Mercury, Engine Oil, Steel, Aluminum, Glass, Copper, Sand, Plastic, Ice, and more • Add, edit, and duplicate custom fluids and materials • Calculation History with auto-save, notes, timestamps, and full input snapshots • Step-by-step worked solutions with substituted values • Formula reference with assumptions, limitations, and worked examples PRIVACY FIRST No accounts. No tracking. No internet required. All calculations and your history stay on-device with SwiftData. Whether you're modeling sedimentation, sizing particles, studying viscosity, or checking that Stokes' Law applies to your flow regime, Stokes' Law Calculator gives you the answer — and shows the work. Thank you for your support, and feel free to visit nitrio.com for more apps for your iOS devices.