I developed this app late last year because I needed the functionality for myself & couldn't find any calculators that did it. I never got around to posting it to Bitcointalk but now that I've passed 500 downloads it seems like an appropriate time.
From the play store description:
As a local & online trader myself I wanted the ability to calculate the amount of a bitcoin purchase or sale based on a specified markup or markdown over the current bitcoin price so I built this app with traders in mind. With the popularity of Localbitcoins.com, regional bitcoin meetups & other local trading activity this app is intended to provide a simple utility for calculating the cost of any given trade.
The app now supports USD, EUR, CNY, GBP, AUD & JPY as well as multiple exchanges.
https://i.imgur.com/qKtZWwL.png
