The formula for converting one currency to another is simply by multiplying it the exchange rate at the time you want to do your conversions. For instance if you want to convert, say £ 40.00 to US dollars, you first get the exchange rate like £ 1.00 = $ 1.4487. Thereafter, you multiply the digits and get your results; 40* 1.4487. Generally, £ 40 is equivalent to $ 57.948. That is all there is, the trick is to get the correct exchange rate.