Overround
How much the implied probabilities of a market add up to above 100%.
Add up the implied probability of every outcome in a market and a fair book totals exactly 100%; the excess is the overround, and it is the same thing as the Vig & No-Vig Calculator expressed as a total. A 105% book has a 5-point overround. When it drops below 100% across two bookmakers, an arbitrage exists.