The risk calculator is a program designed to give you the important overall % odds involved when taking up any casino offer. It tells you the % chance of an overall loss, % chance of ruin (assuming it is not a no-risk offer), % chance of profit and % chance of at least doubling your money. It is designed to be used when you are playing blackjack and assumes that you will be flat betting, i.e. not changing your stake (apart from with doubling and splitting).

Simply fill in the details according to the offer you're looking at. The Software type is currently fixed at Playtech Blackjack, which has a house edge of 0.44%, about the average for casino software. The small variations in house edge between online casino's makes little difference to these percentage figures anyway.

Taking Starluck Casino, a highly recommended iGlobalMedia casino as the example-

The current offer is- Deposit $100, get an instant $100 bonus with a required wager of 1600 as the terms and conditions state that deposit + bonus must be wagered eight times before withdrawing (8*(100+100)). So to use the calculator you'd input 100 into the deposit field, 100 into the bonus and 1600 into the wager

The minimum bet here is $1. Assuming you are going to dollar bets, enter 1 in the stake per hand box.

As you can see, taking up this offer presents a 97% chance of profit, with a probability of only 0.003% that you will lose your total deposit compared to a 39.647% chance that you will more than double your money. 

With the odds so highly in your favour (you'll fail to make a profit only 1 in 30 times on average with this offer), it is clearly an offer well worth taking up.

Playing with higher stakes does significantly increase your chances of making a loss, as you can see by changing the stake per hand figure to 5. However, it does also make the possibility of having a bigger win much more likely and means that completing the wagering will take significantly less time.