Particles Velocity Calculator

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Select a preset gas or choose Custom to enter any molar mass.
Gas temperature. Celsius for metric, Fahrenheit for imperial. Absolute zero is the lower limit.
C
RMS speedFast molecule
506.7

Root-mean-square speed: relates directly to average kinetic energy

Mean speed466.8
Most probable speed413.7
Temperature (K)298.15
Molar mass28.97
_unitLabelm/s
Most probable413.7
Mean466.8
RMS506.7

At 25.0 C, air molecules travel at 506.7 m/s (RMS).

  • The RMS speed (506.7 m/s) is always the largest of the three speeds because squaring amplifies the contribution of fast molecules.
  • The most probable speed (413.7 m/s) is the peak of the Maxwell-Boltzmann distribution, where the greatest number of molecules are found.
  • Mean speed (466.8 m/s) sits between the most probable and RMS values. The fixed ratios are: v_mp : v_mean : v_rms = 1 : 1.128 : 1.225.
  • Halving the molar mass of air (keeping T = 298.1 K) would raise the RMS speed to about 716.5 m/s - a factor of sqrt(2).

Next stepThese speeds assume ideal gas behaviour. At very high pressures or very low temperatures the real speeds deviate from these values.

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