You may want to investigate currency hedging if you have obligations in currency B while you earn currency A. If you are only saving to buy later, I recommend s

You may want to investigate currency hedging if you have obligations in currency B while you earn currency A. If you are only saving to buy later, I recommend settling for "average" rather than playing the fool's game of trying to time the market. Periodically convert A to B (how often depends on what kind of fees you pay to convert and/or transfer: e.g. if there is a fixed cost like a wire transfer fee, try to make that fee take up no more than 1% of your transfer amount). This can loosely be called Dollar Cost Averaging.