Open Question: Position sizing and currency conversion?

Hi i have a question about determining position size in currencies. now i know from the stock market this position size equation $Risk / Ssize = No of shares. now i have managed to convert this to $risk / Pip(x10) = Volume. (pips must be x10 because of the $10 return on Std lots.) So if i risk $1000 by 20 pips. (1000 / 200 = 5 ). equals 5 Std Lots. but this is only correct in my base currency (AUD) So if i buy the EUR/USD for example. the risk will be more then 2 %. Do you have any ideas on how to take this formula and add a currency conversion to it, this needs to work for all currencies.