How long you can lock in your exchange rate will depend on which company you use. Some transfer providers such as Xe offer guaranteed spot prices for 12 to 36 hours. Other companies allow you to lock in the exchange rate you achieve by using a limit order, which means that you specify the exchange rate you wish to achieve and the transfer happens when your desired rate has been reached. Other companies allow you to lock in your exchange rate into the future using a forward contract, which can be anywhere up to a year or more. This is extremely useful if you are doing business internationally and there’s a delay between when you order goods or services and when you pay for them.