Diffusion Coefficient Calculator

Your details

Choose the physical scenario. Stokes-Einstein is best for proteins and nanoparticles in solution; MSD uses single-particle tracking data.
Determines the friction coefficient formula. For ellipsoids, "a" is the semi-major axis and "b" is the semi-minor axis.
Absolute temperature drives the thermal energy kBT that propels diffusion.
degC
Dynamic viscosity of the solvent. Water at 25 degC is 0.89 mPa·s; at 20 degC it is 1.002 mPa·s.
mPa·s
Hydrodynamic radius for a sphere, or the semi-major axis (longest half-axis) for ellipsoids and disks.
nm
Diffusion coefficient (D)
49.0746

How fast the species spreads through the medium

D unitsum2/s
Friction coefficient0N·s/m
49.0746 um2/s
Large particles / viruses<1Large proteins1-50Small proteins50-200Peptides / sugars200-600Small ions / molecules600+

D = 4.907e+1 um2/s

  • The friction coefficient is 8.388e-11 N·s/m, reflecting how strongly the solvent resists the particle.
  • This D is in the range typical of large proteins or folded RNA molecules (1-50 um2/s).
  • Diffusion is strongly temperature-dependent: D roughly doubles for every 10 degC rise in an aqueous system because viscosity drops and thermal energy increases.

Next stepTo find how far a molecule diffuses in a given time, use the Diffusion Time/Distance mode, or pair this result with Fick's Second Law for time-evolving concentration profiles.

 = Powered by OnlyCalculators