Since online gambling has been regulated in Belgium, basically each eligible license holder has complemented their land based operations with an online counterpart. Being such a small country, everyone wants to secure their market share as soon as possible. The big players have been pouring tons of money in to marketing and advertising, it’s everywhere: radio, television, (online) newspapers, bus stops, billboards, sport events, airplane vouchers - you name it. While regulations for land based casinos are very strict and almost overprotective, regulations for online play are much more permissive. This makes that online casinos can be rather aggressive acquiring new customers.

You will often see online casinos hand out free registration bonuses: “You get 10 euro for free when you sign up, no strings attached!". This makes it look like casinos are just handing out free cash right? We should all know better than that though.

There are always conditions to cash out a bonus. Bonuses come in different forms and flavors and preconditions to clear them vary wildly. The Playthrough Bonus is the favorite among players by far; it’s straightforward and requires zero investment.

When you receive a Playthrough Bonus, you receive an amount of bonus money, which can be converted to cash by wagering it a specific amount of times. For example; you receive a Playthrough Bonus of 10 euro, which needs to be wagered 30 times before the bonus is cleared. This means that you need to bet 300 euro (10 euro multiplied by 30) in total to clear the bonus and to receive what’s left off your balance.

So is betting the bonus amount 30 times realistic, or will you always close your browser empty handed with nothing to show for on your balance? The answer depends heavily on the payout rate. This percentage represents how much of the money that goes into the casino, is returned to players. In a formula, this is the wins divided by the bets. This percentage is generally a lot higher than most people expect. Casinos aim for a payout rate between 95 and 99 percent. They want to cultivate a long term relationship with happy and social customers, not clear your bank account as soon as you open the door. Note that the payout percentage is an average, not all games are a smooth ride. Some players like big wins, and big losses, while others feel more comfortable losing small, but don’t mind winning small either. Casinos also prefer a smooth ride, especially when it comes to bonuses. They might even tweak games to have less aggressive, more equally distributed wins when bonus money is in play.

Now let’s look at how much money would be left on our balance when we try to clear a Playthrough Bonus of 10 euro with a playthrough of 30 and a payout percentage of 98.

I defined two records (excuse my primitive obsession). First a Bonus record that contains an amount, a balance, the total amount of bets and a playthrough. A few functions are associated with the Bonus record; they allow the bonus to be created, to bet, to win, to check if it still accepts bets and to check if the bonus has been cleared. The second record, the GameSettings, define the payout percentage and the stake of a bet.

type Bonus = { Amount : decimal; Balance : decimal; Bets : decimal; Playthrough: decimal; }
    with    
        static member Create amount playthrough =
            { Amount = amount; Balance = amount; Bets = 0M; Playthrough = playthrough }       
        member x.Win amount =            
            { x with Balance = x.Balance + amount }
        member x.AcceptsBet amount =
            x.Balance - amount >= 0M
        member x.Cleared =
            ( x.Playthrough * x.Amount ) - x.Bets <= 0M
        member x.Bet amount =
            match x.AcceptsBet amount with
            | true -> { x with Bets = x.Bets + amount; Balance = x.Balance - amount }
            | false -> invalidOp "Bonus can't accept bet" 
type GameSettings = { Payout : decimal; Stake : decimal; }

After defining these structures, I defined a function that recursively keeps playing (bet and win) until either the bonus is cleared, or the bonus no longer accepts bets (out of money).

let rec playUntilCleared ( bonus : Bonus ) settings =          
    match bonus.Cleared with        
    | true -> bonus
    | false -> 
    (         
        let bet = settings.Stake
        let win = settings.Stake / 100M * settings.Payout

        match bonus.AcceptsBet bet with
        | false -> bonus
        | true -> playUntilCleared ( bonus.Bet(bet).Win(win) ) settings            
    )

When we run this function we know the answer to our question. On average, we will clear the bonus with four euro left on our balance.

printfn "%A" ( playUntilCleared ( Bonus.Create 10M 30M ) { Payout = 98M; Stake = 0.2M } )

// {Amount = 10M;
// Balance = 4.000M;
// Bets = 300.0M;
// Playthrough = 30M;}

When we turn down the payout to be one percent lower, we only have 1 euro left on our balance. When we turn it down even more, there won’t be anything left.

Given a few parameters which should be available to you (bonus amount, playthrough and even payout percentage), you can calculate how feasible it is to clear a Playthrough Bonus. Unless variance is on your side, I guess it will rarely turn out to be a lucrative grind.