Partition function may refer to:

• Partition function (statistical mechanics), a function used to derive thermodynamic properties
  • Rotational partition function, partition function for the rotational modes of a molecule
  • Vibrational partition function, partition function for the vibrational modes of a molecule
  • Partition function (quantum field theory), partition function for quantum path integrals
• Partition function (mathematics), generalization of the statistical mechanics concept
• Partition function (number theory), the number of possible partitions of an integer