Use historical exchange rate data (via google or forex api perhaps) per date for currency conversion
Instead of using the current financial exchange rate for all currency conversion, couldn't you query the historical rate at which a transaction date has been set in Splitwise, in order to convert each Splitwise transaction according to its historical exchange rate?
Fluctuating exchange rates for long outstanding groups (e.g. vacations with multi-country/multi-currency roadtrips) force me to use Excel/Spreadsheets to do currency conversion with historically accurate exchange rates. Not having this feature either means paying a sum of settlement that either does not reflect the historical price payed, or forces me to use another program for currency conversion.
Would be nice to see this features :)
Thanks for the suggestion! I definitely see how this makes sense, but we’re unlikely to add historical exchange rates as a feature in the near future.
There are a lot of edge cases like this in currency conversion – for example, if we did implement historical rates, should we use the rate from the day that the expense was added, or the rate from the day that the expense is dated? However, most people aren’t looking for that level of detail, and we think it’s important to keep Splitwise simple as much as possible. That’s why we show the current exchange rate, and then convert all expenses at that rate. It makes currency conversion easier to understand, and we actually found that it’s what most people expect to happen anyway :)
If you’d like a more precise conversion on an expense-by-expense basis, your best bet is probably to export to a spreadsheet (as you mentioned). I realize that’s not a simple process, so I’m sorry for the inconvenience!
Tim Sell commented
You should remember the original currency for every transaction, and the FX close for every date, then you could convert the group into any currency at will at any time. This would be very useful for trips
I'd love to see this feature as well. Taking the historical exchange rate of the day the expense is dated is the only fair / realistic way to handle multi-currency groups / trips. The only reason why I opted into Splitwise Pro was to have this feature as that is what I expected when I read "currency conversion". Just yesterday, I settled up with friends for our Iceland trip of November 2016. The difference between the real historic exchange rate which was used to charge our cards back then and the current exchange rate Splitwise used for ISK -> USD conversion resulted in one of my friend oaying over $100 more than she should have. That's not cool at all! Eventually, I had to review all group expenses, identify the wrongly converted ones and do the conversion manually.
I am a Software Engineer and studied Human Computer Interfaces and User Experience Engineering. My professional judgement would suggest the following change:
* use the historical exchange rate for the day the expense is dated
* in the auto-generated comment, just like on every credit card bill with foreign expenses, put in the original amount in foreign currency, the used exchange rate, the date of the exchange rate, and the resulting amount in the target currency
From a UX perspective, most users won't even notice the difference - it will still be one click on "Convert all to USD" and afterwards all expenses will be in USD, just like they are now. But for the financially / mathematically advanced people like use here, it will be a relieve to see that Splitwise is using the correct exchange rate for each expense.
Tom Parker commented
So, I built a tool to do this. There's a blog post about it at https://tech.labs.oliverwyman.com/blog/2017/04/25/extending-splitwises-currency-conversion/ and the actual tool is at https://moolah-heroku.herokuapp.com/
Tom Parker commented
I've started to build an app to do this externally, but currently running into the problem of http://dev.splitwise.com/dokuwiki/doku.php?id=update_expense not letting you update the currency_code of an existing expense...
Hm, this is disappointing. Splitwise has all the data necessary to make this conversion — I don't set the expense date for my own health!
If the concern is that folks want it at the current exchange rate (though I'm not sure why that'd be preferred), this would already be the default behavior as the bill date defaults to the current date when added.
This is the way that other expense-tracking apps I've used (e.g. Expensify, Concur) work, and I'm surprised to find that Splitwise Pro doesn't do the same. Would make the product a lot more useful for me!
Brad Dworkin commented
I would like the feature to use the exchange rate from the day that the expense is dated. I would prefer this to when the date was added due to the fact i might forget to put in an expense on time