Round-Trip Currency Conversion Loss Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Round-Trip Currency Conversion Loss Calculator
Convert currency A to currency B, then immediately convert it back to A - you will almost never end up with the amount you started with. The gap is the spread: the built-in margin every bank, exchange kiosk, or broker charges between their buy and sell rates.
Final Amount = Starting Amount x Buy Rate x Sell Rate
Example
Starting with $1,000, converting at a buy rate of 0.91 and converting back at a sell rate of 1.08:
Final Amount = 1,000 x 0.91 x 1.08 = $982.80 - a loss of $17.20, or 1.72%.
Why This Happens
Currency exchange providers rarely quote the exact same rate for buying and selling a currency - the difference (the spread) is effectively their profit margin and cost of doing business. This calculator quantifies exactly how much that spread actually costs in a round trip, which is a genuinely useful way to compare different exchange providers, since two providers advertising "no commission" can still have very different embedded spreads that only show up when you do this kind of round-trip math.