If you are converting Euros to US Dollars, you would need to know the current exchange rate. Take for example the current value of 1.19 - this would mean that 1 Euro is equal to 1.19 US Dollars. This can be applied for any amount by just multiplying the conversion value. Moreover, you can convert it the other way around, ie US Dollars to Euro by inverting the conversion value: 1/1.19=0.84 which means that 1 US Dollar is equal to 0.84 Euro.