What Is Interest Rate?
An interest rate is the cost of borrowing money, expressed as a percentage. If you borrow 1,000 dollars at 5% annual interest, you pay 50 dollars per year.
In forex, interest rates are set by central banks and heavily influence currency values. The Federal Reserve sets the US interest rate (currently around 5.25-5.50%). The ECB sets the Eurozone rate (currently around 4.25%). The Bank of Japan sets the Japanese rate (currently around 0.50%).
These rates are the benchmark that everything else is based on. Commercial banks, businesses, and traders all pay rates near or above the central bank’s base rate.
Why Forex Traders Obsess Over Rates
Central bank interest rates are the single most important driver of forex movement.
Simple Rule: Higher interest rates strengthen the currency. Lower interest rates weaken it.
Why? Investors want to earn the highest yield. If US rates are 5% and Eurozone rates are 4%, investors prefer USD (higher yield). They sell EUR, buy USD. EUR/USD falls.
This is mechanical. It’s not opinion. It’s pure yield-seeking behavior.
How Central Banks Change Rates
Central banks adjust rates based on economic conditions:
- Inflation rising? Raise rates to cool demand (strengthen currency)
- Economy slowing? Cut rates to stimulate (weaken currency)
- Crisis? Cut rates sharply to inject liquidity (weaken currency)
When the Fed raises rates 25 basis points (0.25%), the market immediately prices in USD strength. When it signals future cuts, the market prices in USD weakness in advance.
This is why “forward guidance” (the Fed telling you what it will do next) moves markets as much as actual decisions. The market front-runs the policy.
Interest Rate Differentials: The Core Metric
Forex traders care most about the differential—the gap between two rates.
Example: EUR/USD Rate Differential
- Fed Rate (USD): 5.50%
- ECB Rate (EUR): 4.25%
- Differential: 5.50% - 4.25% = 1.25%
This 1.25% differential means holding USD is more profitable than holding EUR. Investors prefer USD. EUR/USD tends to weaken over time (USD strengthens).
But if the ECB raises to 5.00% while the Fed cuts to 5.00%, the differential goes to 0%. The carry advantage disappears. EUR/USD can then move based on other factors.
Interest Rate Cycles: The Trading Macro
Interest rates move in cycles:
Tightening Cycle: Central bank raising rates. Currency strengthens throughout the cycle.
Peak/Pause: Central bank stops hiking and assesses impact. Currency often consolidates or reverses early.
Cutting Cycle: Central bank lowering rates. Currency weakens throughout the cycle.
Most currency trends align with their central bank’s rate cycle. A currency in a hiking cycle often outperforms for 12-24 months. A currency entering a cutting cycle often underperforms.
Smart traders position early in cycles and hold through them.
Swap Points: Your Daily Interest Charge/Reward
When you hold a forex position overnight, you earn or pay interest based on the rate differential. This is called swap or rollover interest.
Long EUR/USD (you own EUR, short USD):
- Earn ECB rate (4.25%)
- Pay Fed rate (5.50%)
- Net: Owe 1.25% annually (negative swap)
- Daily cost: 1.25% ÷ 365 = 0.00342% per day
On 1 standard lot (100,000 EUR), that’s ~3.42 EUR per day in swap costs.
Long AUD/USD (you own AUD, short USD):
- Earn Australian rate (4.35%)
- Pay Fed rate (5.50%)
- Net: Owe 1.15% annually (negative swap)
- But AUD/USD might appreciate due to risk-on sentiment, offsetting swap costs
Long USD/JPY (you own USD, short JPY):
- Earn Fed rate (5.50%)
- Pay BOJ rate (0.50%)
- Net: Earn 5.00% annually (positive swap)
- Daily reward: 5% ÷ 365 = 0.0137% per day
On 1 lot (100,000 USD), you earn ~1,370 JPY per day just for holding.
This is why carry traders love USD/JPY—the rate differential is huge.
Real Rates vs. Nominal Rates
Nominal rate is what the central bank sets (5.50% Fed rate).
Real rate accounts for inflation (nominal rate minus inflation rate).
If inflation is 3%, the Fed’s 5.50% nominal rate is really a 2.50% real rate in terms of purchasing power.
High real rates (nominal minus inflation) are more attractive to investors. If US inflation is low but rates are high, real rates are high. That’s USD strength.
If Eurozone inflation is high but rates are moderate, real rates are low. That’s EUR weakness.
Sophisticated traders track real rates, not just nominal.
Interest Rate Expectations: The Market’s Pricing
Forex markets don’t price actual rates; they price expected rates.
If the Fed is expected to cut rates next quarter but hasn’t yet, USD is already weakening in anticipation. When the actual cut happens, the market has already repriced it. The actual cut might not move USD much.
This is why the “sell the news” pattern exists. The big move happens on expectation (forward guidance). The actual announcement is met with indifference or reversal.
Historical Interest Rate Trends
Japan: Low rates for 30 years (ZIRP—zero interest rate policy). Only recently normalizing. JPY was “risk-off” currency for decades (borrow cheap in JPY, invest elsewhere).
US: Rising to 5.5% in 2023-2024. Making USD attractive. USD strengthening.
Eurozone: More moderate (4.25%). Caught between inflation and growth concerns.
UK: Higher than EU average (5.25%) due to inflation fighter. GBP support from higher real rates.
Australia: High rates (4.35%) supporting AUD. But slowing economy might force cuts.
These cycles explain why some currencies outperform others year to year.
Interest Rates and Inflation: The Trade-off
Traders debate constantly: “Will the Fed cut rates?” Answer depends on inflation.
If inflation is coming down, cuts likely. If inflation is rising, cuts unlikely (hikes possible).
This trade-off is THE debate in markets. Inflation data is watched obsessively. Every inflation print moves the entire forex market.
Tracking Interest Rate Impact
When you log a trade, note:
- Interest rate differential: Why you took the trade
- Rate expectations: What you thought central banks would do
- Actual moves: What actually happened
- Did your thesis play out?: Was the rate move what you expected?
Over time, you’ll see whether your interest rate forecasts are any good. Most traders are terrible at predicting rate cycles. But if you’re consistently right, that’s a profitable edge.
PipJournal Tracks Your Interest Rate Edge
PipJournal logs every trade with interest rate context—the rate differential when you entered, central bank guidance, and what happened. Over time, you’ll see if you have genuine edge trading interest rate cycles. Maybe you’re great at predicting when the Fed will cut, but terrible at timing tops. PipJournal’s AI reveals your actual interest rate edge.
