Enter in the amount you wish to bet, and the odds for the teams (in decimal/European format - you may need to change this in your profile), and the calculator will do the rest. You'll get how much to bet on each team, and also the calculated winnings as both an absolute number  (i.e. the amount you're expected to profit) and as a percentage profit.

If the odds are so far apart on some matches, why does the bet have to be equal between the two options? If the underdog is so heavily out of favour, is there more profit to be had by betting heavier on the favourite? The answer is, of course, YES! Enter the odds for the two teams as normal, but also enter the minimum profit percentage you want from a card (2.27% is equivalent to $1 a day profit if spending 5000G (4400 SB) and 0 would be break even). The calculator then works out the bet value that will give you approximately your minimum profit on the underdog, and then maximizes your winnings for the heavy favourite. 

At this time, it will not warn if your bet on the favourite pays out under your minimum entered profit, so make sure you check before betting!