Same as sensible cooling load.(but don't add it to cooling load)
Q = 1.09 x cfm x (T2-T1)
T1 = coil exit temperature
T2 = Any intermediate temperature(based on duct heat load)between room condition and coil exit temperature.
When you calculate total load and know the apparatus dewpoint and plot it on a psychrometric chart you will come to know whether reheating is required or not. Keep in mind that the return air temperature in both reheating and no reheating conditions is same.
We provide reheat as we are cooling down the air below the required temperature condition to reduce moisture.
You need not add it to your cooling load. The formula I provided above is heating load.
