Bittner vs Hughes – Nerdtastic Restaurant Bill Splitting

Splitting restaurant bills is an awkward business. In the US and many other countries, most restaurants are unwilling to create a separate check for each guest.  As a result, many a lovely night of dining out ends with an awkward fairness problem.

One appealing solution is to just “split the bill,” because the math is easy and everyone contributes. Here the awkwardness is for people living on a tight budget. No one wants to start a fight about a spare change, but a dinner out often crosses the line into real money. If you’re being spendthrift and go out with less thrifty friends, splitting a check can torpedo your spending cash for the week. It’s hardly fair for someone who is broke and orders an appetizer to split with someone who had a few drinks and a main course.

Paying for what you owe rarely works out either. People do their math wrong, forget what they ordered, or don’t have exact change or cash on hand. Quite often there is too little money on the table to pay the bill and leave an appropriate tip. Having to discuss what each person ate and calculate for them is awkward, especially if you have to tell them they underpaid and few people enjoy thinking hard about this.

The worst outcome is that you stop going out with those friends, losing a friendship over a seemingly simple issue of financial courtesy. Both approaches are fraught with problems. What solutions does the internet have for us? How can Splitwise help?

In this article, our resident fairness humorist Nellie and fairness researcher Jon will review and debate which innovative new solutions actually make practical sense for real people in the real world. We will discuss “Credit Card Roulette,” calculator, and the most recent piece of innovative technology: “Expectorant.” Splitwise has yet to divise it’s own calculator – this is a hard problem, even for astrophysicists.

Credit Card Roulette

Jon: So Nellie, I’m kind of a fan of this thing called credit card roulette: put everyone’s credit card in a hat and pick one. That person pays the check. I like it because it’s simple, it’s funny, and with the right crowd, it makes for a good laugh. Plus, the odds are better than Vegas! If people like gambling, they should love credit card roulette.

Nellie: So, you’re asking me to take the chance of paying everyone’s bill at the table, no matter what gets ordered? That’s one contest I have no interest in winning. First, I don’t get to eat out much. The chances of me eating with the same group of people enough to have this possibly work out “fairly” in the end will never, ever happen in 1000 years.

Maybe it’s because my financial footing isn’t as sturdy as I’d like it to be, or maybe it’s that I really am that cheap that I want to only pay what my share is. Either way,  I can’t see myself getting into this dinner game anytime soon.


Jon: Ok, fair enough. The problem is that the math you are talking about is pretty hard, even for me. So here is this article on about a way to split your restaurant bill using the expectorant.

If you’re not a stickler for fairness and social efficiency, the hands-down fastest solution is  That person pays the whole bill. If everyone happened to have spent the same amount, then credit card roulette is also perfectly fair.

The question, then, is how to get as close as possible to the convenience of credit card roulette but with perfect fairness: everyone pays, in expectation, exactly what they owe. Fortunately, and perhaps surprisingly, we don’t need to figure out who ordered what — for the most part — in order to achieve this.

Here’s what you do! Start with any item on the bill. The person who ordered that item pays the bill with probability equal to the cost of that item divided by the subtotal. If that person is it, then you’re done. If not, then subtract that item from the subtotal and repeat, recursively, with another arbitrary item. If you start with expensive items then you’ll probably find the person who’s paying after a handful of items, but it doesn’t matter for fairness what order you pick things in. You won’t have to figure out all the confusing drinks and appetizers (yet the outcome is as fair as if you had!).

Nellie: I still have a hard time getting behind this. I could see myself using it – though only when trying to gain nerd cred with my dinner guests though. Yes, math is fun – but paying for everyone’s dinner is not. Second, as much math and fancy wording you want to throw at it – this expectorant method still feels like gambling to me. It would be just as fast to do the math of what you are paying for. If simple addition between a few items on a dining bill isn’t easier then this weird roulette thing, then you may have a problem.

Maybe it’s the questionable friend choices I’ve made in life (or vice versa); But I would bet that the credit card roulette or expectorant method would be used once at dinner, and then never ever again – mostly due out of frustration by the person who “won” the first time.

My idea of the best way to split the dinner bill is to actually split it fairly, with something like Yes, you’ll need to input data in a device to track it.. and yes, not everyone may have the exact change when it comes to ponying up the cash for their meal. Honestly though, who cares!? I’d rather be out a couple of bucks than out of a whole table’s meal. Besides, you’d get to shame the person who came short changed for not being able to do simple math in their head when ordering – how is that not great tableside entertainment?!

Even though in theory we’ve all got the same chance to be the lucky winner, I just can’t get excited about “winning” when it comes to the credit card roulette or the expectorant method. By using something like to track dinner bills, as boring as it may be – just feels the fairest to me.

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