How does Backpack calculate its exchange rate? Backpack Support February 06, 2018 10:15 Updated Follow Currently, we are charging BDT84.5/USD. We are charging this amount based on the “HSBC Bangladesh dollar sales rate”. You can see this PDF for reference http://bit.ly/2nMSRo8; here the USD cash sales rate has been taken into account. Related articles Do I have to make payment in advance? What is the 9% sales tax that I see in the item? Why is there a shipping charge added to my item? How do I pay for items? How much are you charging for an item? Comments 0 comments Please sign in to leave a comment.