You can calculate theoretical iodine value based on number of unsaturation in a compound with known molecular mass and weight. For example the theoretical iodine value of 100 g of linoliec acid would  be 181 based on calculation as follows

100/280.44 =0.356 moles of LA

Ratio of iodine required for each double bond is 1:2

For 0.356 moles would be 0.356*4= 1.42*127=180.84 ~ 181.0

Hope this explanation helps you.