Go to the website of a major currency converter; some are displayed in the Resources section.
Enter the amount of pounds you want to convert into the first box and select "GBP" from the drop-down menu.
Select "USD" in the second drop-down menu and click "Convert" to see how many dollars are in your pounds.
Go to a currency exchange booth in the U.S. or U.K. to exchange your pounds. In Britain, any Royal Mail Post Office branch will convert your currency. International airports on both sides of the pond will also buy and sell currency if you wait until your traveling has already begun before converting. Alternately, you can order dollars from your bank.
Submit the amount of pound notes you would like converted to the agent and ask how many dollars you can buy for the pounds you have.
Agree to the price set by the agent if you still want to convert your pounds.
Hand over your pounds to receive American dollars.
Count the dollars you receive before leaving the window.