diff --git a/include/cantera/base/ct_defs.h b/include/cantera/base/ct_defs.h
index 7b4563b36..2723a1f9c 100644
--- a/include/cantera/base/ct_defs.h
+++ b/include/cantera/base/ct_defs.h
@@ -53,61 +53,79 @@ using std::isnan; // workaround for bug in libstdc++ 4.8
 const double Pi = 3.14159265358979323846;
 
 /*!
- *   @name Variations of the Gas Constant
- * %Cantera uses the MKS system of units. The unit for moles
- * is defined to be the kmol.
+ * @name Defined Constants
+ * These constants are defined by CODATA to have a particular value.
+ * https://physics.nist.gov/cuu/Constants/index.html
  */
 //@{
 
-//! Avogadro's Number [number/kmol]
+//! Avogadro's Number \f$ N_{\mathrm{A}} $\f [number/kmol]
 const double Avogadro = 6.02214076e26;
 
-//! Boltzmann's constant [J/K]
+//! Boltzmann constant \f$ k $\f [J/K]
 const double Boltzmann = 1.380649e-23;
 
-/// Universal Gas Constant. [J/kmol/K]
+//! Planck constant \f$ h $\f [J-s]
+const double Planck = 6.62607015e-34;
+
+//! Elementary charge \f$ e $\f [C]
+const double ElectronCharge = 1.602176634e-19;
+
+/// Speed of Light in a vacuum \f$ c $\f [m/s]
+const double lightSpeed = 299792458.0;
+
+//! One atmosphere [Pa]
+const double OneAtm = 1.01325e5;
+
+//! One bar [Pa]
+const double OneBar = 1.0E5;
+
+//@}
+
+/*!
+ * @name Measured Constants
+ * These constants are measured and reported by CODATA
+ */
+//@{
+
+//! Fine structure constant \f$ \alpha $\f []
+const double fineStructureConstant = 7.2973525693e-3;
+
+//! Electron Mass \f$ m_e $\f [kg]
+const double ElectronMass = 9.1093837015e-31;
+
+//@}
+
+/*!
+ * @name Derived Constants
+ * These constants are found from the defined and measured constants
+ */
+//@{
+
+//! Reduced Planck constant \f$ \hbar $\f [m2-kg/s]
+const double Planck_bar = Planck / (2 * Pi);
+
+//! Universal Gas Constant \f$ R_u $\f [J/kmol/K]
 const double GasConstant = Avogadro * Boltzmann;
 
 const double logGasConstant = std::log(GasConstant);
 
-//! One atmosphere [Pa]
-const double OneAtm = 1.01325e5;
-const double OneBar = 1.0E5;
-
 //! Universal gas constant in cal/mol/K
 const double GasConst_cal_mol_K = GasConstant / 4184.0;
 
-/// Planck's constant. [J-s]
-const double Planck = 6.62607015e-34; // J-s
-const double Planck_bar = Planck / (2 * Pi); // m2-kg/s
+//! log(k_b/h)
+const double logBoltz_Planck = std::log(Boltzmann / Planck);
 
-/// log(k/h)
-const double logBoltz_Planck = std::log(Boltzmann / Planck); // ln(k_B/h)
-/// Stefan-Boltzmann constant
-const double StefanBoltz = 5.670374419e-8;
+//! Stefan-Boltzmann constant \f$ \sigma $\f [W/m2/K4]
+const double StefanBoltz = Pi * Pi * std::pow(Boltzmann, 4.0) / (60.0 * std::pow(Planck_bar, 3.0) * lightSpeed * lightSpeed); // 5.670374419e-8
 
-//@}
-/// @name Electron Properties
-//@{
-const double ElectronCharge = 1.602176634e-19; // C
-const double ElectronMass = 9.1093837015e-31; // kg
+//! Faraday constant \f$ F $\f [C/kmol]
 const double Faraday = ElectronCharge * Avogadro;
-//@}
 
-/// @name Electromagnetism
-/// %Cantera uses the MKS unit system.
-//@{
-
-/// Speed of Light (m/s).
-const double lightSpeed = 299792458.0;
-
-//! Fine structure constant []
-const double fineStructureConstant = 7.2973525693e-3;
-
-/// Permeability of free space \f$ \mu_0 \f$ in N/A^2.
+//! Permeability of free space \f$ \mu_0 $\f [N/A2]
 const double permeability_0 = 2 * fineStructureConstant * Planck / (ElectronCharge * ElectronCharge * lightSpeed);
 
-/// Permittivity of free space \f$ \epsilon_0 \f$ in F/m.
+//! Permittivity of free space \f$ \varepsilon_0 $\f [F/m]
 const double epsilon_0 = 1.0 / (lightSpeed * lightSpeed * permeability_0);
 
 //@}