For a given state

```
E = -hbar gamma m B
m is one of (-1/2;1/2) proton spin states
gamma - proton gyromagnetic ratio in 1/(Tesla*s)
hbar - reduced Planck constant in m2kg/s
```

Difference between two states of a proton will be

```
|delta E| = hbar gamma B
```

Substitute values into the formula and get delta E in Joules or convert to other energy units.