I’ve written a script to solve a problem that I’ve been having recently; when calculating expenses while working abroad, I never know what exactly to use as the exchange rate – on the day of submission, at the beginning? etc…

I’ve settled on calculating the average exchange rate between the date the claim began, and it ends. To make this easier I’ve created a PHP page that calculates this given a start and end date.

You can find it over at http://www.chrismaddern.com/currency

Currently it works only with USD -> GBP, however the API has data for about a dozen currencies so I’ll implement more in the next few days.

Bug reports etc… in the comments.