How this instrument works
A currency forward is not a guess about where a currency will trade later — it is the price implied today by the gap between two interest levels, so that borrowing in one currency, converting at spot, and lending in the other produces no riskless profit once the position is reversed at that forward price. That no-arbitrage condition is called covered interest parity, and it lets a bank quote a ninety-day forward the moment you ask, without forecasting anything.
A corporate treasurer paying a foreign supplier in ninety days, an exporter expecting foreign-currency revenue, or a fund manager hedging an overseas bond position all face the same question: what price can they lock in now? This instrument answers it directly from the spot rate and the two interest levels involved, rather than from a market view of where the currency is headed.
The formula's shape follows the logic exactly: raise the domestic interest level and the forward price rises, because money left in the domestic currency now earns more, so covered arbitrage requires the forward to sell the foreign currency at a richer domestic-currency price later. Quoted bank forwards can still drift a few basis points from this textbook figure because of transaction costs, credit risk, and funding frictions the formula assumes away.
- Enter the Spot exchange rate — the current price of one currency in terms of the other.
- Set the Domestic interest rate, % — the annual rate available in the currency you are pricing from.
- Set the Foreign interest rate, % — the annual rate available in the other currency.
- Read the Forward exchange rate the instrument computes from the interest rate gap between the two.
Worked example — a 1.10 spot rate with a 5% vs 3% interest gap
Take the golden case: a spot rate of 1.10, a 5% domestic interest level, and a 3% foreign interest level. The formula multiplies 1.10 by 1.05, then divides by 1.03, which gives a forward price of 1.121359 — the exact figure this instrument reads out from the same three inputs.
That is a two-percentage-point interest gap producing roughly a 1.24% forward premium on the foreign currency, and the relationship is close to linear, so widening the gap to four points would roughly double the premium. Nothing here forecasts the future spot price; it only prices today's no-arbitrage forward.
Questions
Does the forward price predict where the exchange rate will actually go?
No. It is a no-arbitrage price derived only from the interest gap between two currencies, not a forecast. Whatever the market expects about the future is already priced into today's spot rate and the interest levels themselves; the forward price keeps that combination free of riskless profit — it does not add a prediction on top.
Why does raising the domestic interest level push the forward price higher?
Because money parked in the domestic currency now earns more interest, anyone converting to the foreign currency, lending it, and converting back later must be compensated with a richer forward price — otherwise the higher domestic level would let traders profit from the gap with no risk, and that gap gets arbitraged away almost instantly in liquid markets.
What is the difference between the forward rate and the forward premium?
The forward rate is the actual price quoted for future delivery, in the same units as the spot rate. The forward premium (or discount) is that same gap expressed as a percentage of spot, usually annualized, so a currency can be described as trading at a '2% forward premium' rather than quoting the full figure.
Who actually calculates a forward price this way?
Corporate treasurers pricing a hedge before a bank quotes it, FX traders checking whether a quoted forward sits close to the textbook no-arbitrage price, and finance students working through covered interest rate parity all use this same three-input formula rather than reading a forward straight off a screen.
Why might a bank's actual forward quote differ from this figure?
Real quotes bake in a bid-ask spread, counterparty credit risk, and funding costs this formula assumes away. Since the 2008 financial crisis those frictions have widened what traders call the cross-currency basis, so quoted forwards can sit a few basis points off the textbook covered interest rate parity figure even in major, liquid currency pairs.
What happens to the forward price when both interest levels are equal?
It equals the spot rate exactly. With no interest gap there is nothing left for the forward to compensate for, so the currency prices flat between now and the delivery date. Widen the gap in either direction and the forward moves away from spot in proportion to that difference.
References
- Federal Reserve Board — H.10 Foreign Exchange Rates
- NBER — Deviations from Covered Interest Rate Parity
Read this first: This instrument shows arithmetic, not advice. Real offers add fees, taxes and terms that vary by lender and place — verify the figures against your actual paperwork before deciding anything.