Dinner-math is hard enough when everyone is paying for themselves. It gets much harder when couples want to pay as a unit, and is near impossible when some people expect to pay an exact amount and other people want to pay as two people.
Shares make it all better. When you edit a shared bill, you can set someone’s participation amount as 1, 2, or more shares. One share is an even-split as today; two shares is an even-split for two peoples’ amount, and so on.
For example, suppose Homer, Marge, and Flanders spend $45 on dinner. They decide to split the bill evenly, but Homer pays for himself and Marge.
We considered also exposing percentages and ratios. However, we were concerned that these would require a more clunky and complex interface which would force you to set a percentage amount for everyone, not just for yourself. If people do need this advanced level of control, we can add it, but for now we’re taking the more elegant approach of shares.