The conversion factors in the following table are derived by the physical constants of:
Light speed in vacuum: $c = 299\ 792\ 458\ \texttt{m}\cdot \texttt{s}^{\texttt{-1}}$ ; Planck constant: $h = 6.626\ 070\ 15 \times 10^{-34}\ \texttt{J}\cdot \texttt{s}$ ; Ideal gas constant: $R = 8.314\ 462\ 618\ \texttt{J}\cdot \texttt{mol}^{\texttt{-1}}\cdot \texttt{K}^{\texttt{-1}}$ ;
Avogadro's constant: $N_A = 6.022\ 140\ 76 \times 10^{23}\ \texttt{mol}^\texttt{-1}$ ; Elementary charge: $e = 1.602\ 176 \ 634 \times 10^{-19}\ \texttt{C}$ .
These values should be consistent with the NIST Reference.

 Energy Conversion Table \ hartree eV cm-1 kcal/mol kJ/mol °K J Hz hartree 1 27.211 386 246 219474.63 627.509 474 2625.5 315775.0 4.359 744 72 ×10-18 6.579 683 92 ×10+15 eV 0.036 749 3 1 8065.54 23.060 548 96.485 332 11604.5 1.602 176 63 ×10-19 2.417 989 24 ×10+14 cm-1 4.556 335 25 ×10-06 1.239 841 98 ×10-04 1 0.002 859 14 0.011 962 7 1.438 777 1.986 445 86 ×10-23 2.997 924 58 ×10+10 kcal/mol 0.001 593 60 0.043 364 1 349.755 1 4.184 503.220 6.947 695 46 ×10-21 1.048 539 38 ×10+13 kJ/mol 0.000 380 88 0.010 364 3 83.593 47 0.239 006 1 120.272 4 1.660 539 07 ×10-21 2.506 069 25 ×10+12 °K 0.000 003 166 81 0.000 086 173 3 0.695 035 0.001 987 20 0.008 314 46 1 1.380 649 00 ×10-23 2.083 661 91 ×10+10 J 2.293 712 28 ×10+17 6.241 509 07 ×10+18 5.034 116 57 ×10+22 1.439 326 19 ×10+20 6.022 140 76 ×10+20 7.242 970 52 ×10+22 1 1.509 190 18 ×10+33 Hz 1.519 829 85 ×10-16 4.135 667 70 ×10-15 3.335 640 95 ×10-11 9.537 076 27 ×10-14 3.990 312 71 ×10-13 4.799 243 07 ×10-11 6.626 070 15 ×10-34 1

Alternatively, another version of conversion table in %+E format is available.

Calorie, or more specifically, thermochemical calorie, is defined as an exact number of $4.184\ \texttt{joule}$, i.e. $$1\ \texttt{cal} \equiv 4.184\ \texttt{J}$$ The conversion between mass $m$ and energy $E$, is
$$E = mc^2$$ where $m$ is the mass, and light speed in vacuum $c$ is $299\ 792\ 458\$ meter per second ($\texttt{m}\cdot \texttt{s}^{\texttt{-1}}$). In addition,
$$E = h\nu = h\frac{c}{\lambda}$$
where $\nu$ is frequency (in the unit of hertz, $\texttt{Hz}$ or $\texttt{s}^{\texttt{-1}}$), $\lambda$ is wavelength, and $h$ is Planck constant, $6.626\ 070\ 15 \times 10^{-34}\ \texttt{J}\cdot \texttt{s}$.

The energy of $1\ \texttt{Hz}$ (or $1\ \texttt{s}^\texttt{-1}$), is then equivalent to $$E = h\nu = ( 6.62607015 \times 10^{-34}\ \texttt{J}\cdot \texttt{s} ) \times ( 1\ \texttt{s}^\texttt{-1} ) = 6.62607015 \times 10^{-34}\ \texttt{J} = 6.62607015 \times 10^{-31}\ \texttt{kJ}$$ Note that the unit $\texttt{J}$ here, is the energy in the unit of $\texttt{joule per particle}$ (or $\texttt{ per atom}$, or $\texttt{ per molecule}$, depending on the system being described). Multiplied by the Avogadro's constant $N_A,\ 6.022\ 140\ 76 \times 10^{23}\ \texttt{mol}^\texttt{-1}$, we have the energy conversion of $1 \ \texttt{Hz}$ to $3.990\ 312\ 712 \times 10^{-10} \ \texttt{J}\cdot \texttt{mol}^{\texttt{-1}}$ ($\texttt{joule per mole}$) or $3.990\ 312\ 712 \times 10^{-13} \ \texttt{kJ}\cdot \texttt{mol}^{\texttt{-1}}$ ($\texttt{kilojoule per mole}$) as: \begin{align} E & = (6.62607015 \times 10^{-34}\ \texttt{J}) \times (6.02214076 \times 10^{23}\ \texttt{mol}^\texttt{-1}) \\ & = 3.990312712 \times 10^{-10} \ \texttt{ J}\cdot \texttt{mol}^{\texttt{-1}} \\ & = 3.990312712 \times 10^{-13} \ \texttt{kJ}\cdot \texttt{mol}^{\texttt{-1}} \end{align} Further divided by $4.184$, it is $\ 9.537\ 076\ 272 \times 10^{-14} \ \texttt{kcal}\cdot \texttt{mol}^{\texttt{-1}}$ ($\texttt{kilocalorie per mole}$).

The multiplicative inverse (reciprocal) of wavelength, $\lambda^{-1}$, is another frequently used equivalence to energy in atomic and molecular spectroscopy. The reciprocal of centimeter, $\texttt{cm}^\texttt{-1}$, is defined as $\texttt{wavenumber}$ and intepreted as number of waves per centimeter. In that sense, energy with $1\ \texttt{Hz}$ of frequency is equivalent to $3.335\ 640\ 951 \times 10^{-11}\ \texttt{cm}^{\texttt{-1}}$, by $$E = h\nu = h\frac{c}{\lambda}$$ $$\frac{1}{\lambda} = \frac{\nu}{c} = \frac{ 1\ \texttt{s}^{\texttt{-1}} }{ 299792458 \times 10^2\ \texttt{cm}\cdot \texttt{s}^{\texttt{-1}} } = 3.335640951 \times 10^{-11}\ \texttt{cm}^{\texttt{-1}}$$

The gas constant $R$, is $8.314\ 462\ 618\ \texttt{J}\cdot \texttt{mol}^{\texttt{-1}}\cdot \texttt{K}^{\texttt{-1}}$ (or $0.082\ 057\ 338\ \texttt{L}\cdot \texttt{atm}\cdot\texttt{mol}^{\texttt{-1}}\cdot \texttt{K}^{\texttt{-1}}$). Divided by the Avogadro's constant $N_A$, we have: $$\frac{R}{N_A} = \frac {8.314462618\ \texttt{J}\cdot \texttt{mol}^{\texttt{-1}}\cdot \texttt{K}^{\texttt{-1}}}{6.02214076 \times 10^{23}\ \texttt{mol}^\texttt{-1}} = 1.380649\times 10^{-23}\ \texttt{J}\cdot \texttt{K}^{\texttt{-1}} = k_B$$ $k_B$ is the Boltzmann constant. We can say that $R$ is used to describe the properties of 1 $\texttt{mol}$ of gas, while $k_B$ is used to describe the properties of one single gas molecule. By the relation of $$E = k_B T$$ where $T$ is temperature in the unit of Kelvin $(\texttt{K})$, we can express the energy equivalence in the unit of absolute temperature. Electromagnetic wave with $1\ \texttt{Hz}$ of frequency is then converted to $4.799\ 243\ 073 \times 10^{-11}\ \texttt{K}$ via: $$T = \frac{E}{k_B} = \frac {6.62607015 \times 10^{-34}\ \texttt{J}}{1.380649\times 10^{-23}\ \texttt{J}\cdot \texttt{K}^{\texttt{-1}}} = 4.799243073 \times 10^{-11}\ \texttt{K}$$

The electron volt ($\texttt{eV}$) is one of the units of energy defined by the amount of energy gain or lost by the charge of one single electron moved across an electric potential difference of 1 $\texttt{volt}$. Since that 1 $\texttt{volt}$ = 1 $\texttt{J}\cdot \texttt{C}^{\texttt{-1}}$ ($\texttt{joule per coulomb}$) and the charge of the electron is $-1.602\ 176 \ 634 \times 10^{-19}\ \texttt{C}$, we have $$1\ \texttt{eV} = (1.602176634 \times 10^{-19}\ \texttt{C}) \times (1\ \texttt{J}\cdot \texttt{C}^{\texttt{-1}}) = 1.602176634 \times 10^{-19} \texttt{J}\ \ (\texttt{joule per electron})$$ Multiplied by the Avogadro's constant $N_A$, $$1\ \texttt{eV} = \frac{(1.602176634 \times 10^{-19}\ \texttt{J}) \times (6.02214076 \times 10^{23}\ \texttt{mol}^\texttt{-1})}{10^3} = 96.485332\ \texttt{kJ} \cdot \texttt{mol}^\texttt{-1}$$

The $\texttt{hartree}$ energy (named after Douglas Rayner Hartree), also denoted as $\texttt{Eh}$ or atomic unit in energy ($\texttt{a.u.}$), is a large unit in energy frequently used in computational chemistry. It is suggested by NIST CODATA (2018) with a conversion factor of:
$$1\ \texttt{hartree} = 27.211\ 386\ 245\ 988\ (53)\ \texttt{eV}$$

The table below was taken from http://mccammon.ucsd.edu/~dzhang/energy-unit-conv-table.html.

Most of these numbers have been taken from an old book by Karplus and Porter.
To convert from a unit Y in the left hand column to a unit X in the top row,
mutiply by the table element, MX,Y. Example:
1 hartree = 27.2107 eV
When accuracy is very important, I recommend going instead to the NIST website: Fundamental Physical Constants from NIST
Energy Conversion Table

hartree eV cm-1 kcal/mol kJ/mol oK J Hz
hartree 1 27.2107 219 474.63 627.503 2 625.5 315 777. 43.60 x 10-19 6.57966 x 10+15
eV 0.0367502 1 8 065.73 23.060 9 96.486 9 11 604.9 1.602 10 x 10-19 2.418 04 x 10+14
cm-1 4.556 33 x 10-6 1.239 81 x 10-4 1 0.002 859 11 0.011 962 7 1.428 79 1.986 30 x 10-23 2.997 93 x 10+10
kcal/mol 0.001 593 62 0.043 363 4 349.757 1 4.18400 503.228 6.95 x 10-21 1.048 54 x 10+13
kJ/mol 0.000 380 88 0.010 364 10 83.593 0.239001 1 120.274 1.66 x 10-21 2.506 07 x 10+12
oK 0.000 003 166 78 0.000 086 170 5 0.695 028 0.001 987 17 0.008 314 35 1 1.380 54 x 10-23 2.083 64 x 10+10
J 2.294 x 10+17 6.241 81 x 10+18 5.034 45 x 10+22 1.44 x 10+20 6.02 x 10+20 7.243 54 x 10+22 1 1.509 30 x 10+33
Hz 1.519 83 x 10-16 4.135 58 x 10-15 3.335 65 x 10-11 9.537 02 x 10-14
4.799 30 x 10-11 6.625 61 x 10-34 1