Interest rate differential & carry trade calculator
Pick two currencies: the rates come from our central bank rates table (checked 27 Oct 2026) and you can change them. Add the position size and the days to see what the rate difference is worth.
How to use it
- Choose the pair's currencies in order: for USD/JPY the base is USD and the quote is JPY.
- Check the two rates: they are today's policy rates from the table; type your broker's numbers if you have them.
- Choose buy or sell, the size in lots and how many days you plan to hold.
- The result shows the rate difference and the estimated carry per day, per year and for your days, in the base currency.
Questions
What is the interest rate differential in forex?
The difference between the policy interest rates of the two currencies in a pair, for example the Fed rate minus the Bank of Japan rate for USD/JPY. A positive differential means the first (base) currency pays more.
What is a carry trade?
Buying the higher-yielding currency against the lower-yielding one to earn the rate difference while the trade is open. The exchange rate can move against you by far more than the carry earns.
Is this what my broker pays or charges?
No. Brokers use interbank rates plus their own markup, charge three days on Wednesday (or another day) and often charge on both sides. Your broker's swap table is what counts; this is the theory behind it.
How is the carry calculated here?
Position size in base currency (1 standard lot = 100,000 units) × rate difference ÷ 100 ÷ 365 for one day, times the number of days. A short position reverses the sign.