Have you ever wondered what actually moves currency exchange rates? Why does 1 USD = 0.89 EUR today but 0.85 EUR next month? Why does the Japanese yen move 2% in a single day after a Bank of Japan announcement, but barely budges on a quiet Tuesday?
In this guide, we'll explain how exchange rates are determined — the difference between floating and pegged currencies, the role of supply and demand, central bank intervention, and what actually moves currency pairs day-to-day.
Floating vs. pegged exchange rates
There are two main types of exchange rate regimes:
Floating exchange rates
Most major currencies — USD, EUR, GBP, JPY, CAD, AUD, CHF — have floating exchange rates. This means the rate is determined by supply and demand in the foreign exchange market. Central banks can influence the rate through monetary policy (raising/lowering interest rates, quantitative easing), but they don't fix the rate to a specific level.
Floating rates fluctuate constantly — typically within 0.5% per day for major pairs, but can move 2–5% on volatile days (e.g., around major economic releases or geopolitical events).
Pegged (fixed) exchange rates
Some currencies are pegged to another currency (usually the USD) at a fixed rate. The central bank maintains the peg by buying/selling its own currency on the open market. Examples:
- UAE Dirham (AED): Pegged to USD at 1 USD = 3.6725 AED since 1997.
- Hong Kong Dollar (HKD): Pegged to USD at 7.75–7.85 HKD per USD via a currency board.
- Saudi Riyal (SAR): Pegged to USD at 3.75 SAR per USD.
- Qatari Riyal (QAR): Pegged to USD at 3.64 QAR per USD.
- Bahraini Dinar (BHD): Pegged to USD at 0.376 BHD per USD.
Pegs are typically used by countries with significant export revenues (oil in the case of UAE, Saudi Arabia, Qatar) that want stability for trade purposes. To maintain a peg, the central bank must hold large foreign currency reserves — typically equivalent to several months of imports.
Managed floats
Some currencies operate a "managed float" — the rate is determined by the market, but the central bank intervenes to keep it within an unofficial target band. Examples:
- Chinese Yuan (CNY): The People's Bank of China sets a daily reference rate and allows trading within a ±2% band around it.
- Singapore Dollar (SGD): Managed against an undisclosed basket of currencies.
Supply and demand: the fundamental driver
For floating currencies, the exchange rate is ultimately determined by supply and demand in the foreign exchange market. The forex market is the largest financial market in the world — about $7.5 trillion in daily volume.
When more people want to buy EUR with USD than want to sell EUR for USD, the EUR/USD rate goes up (the EUR strengthens). When the opposite is true, the rate goes down.
The main drivers of supply and demand are:
- Trade flows: If Germany exports more cars to the US than the US exports to Germany, there's net demand for EUR (the German exporters convert their USD revenue to EUR to pay workers and taxes).
- Capital flows: If US investors buy German bonds, they convert USD to EUR to do so — increasing demand for EUR.
- Interest rate differentials: Capital tends to flow to higher-yielding currencies. If the Fed raises rates to 5% and the ECB keeps rates at 3%, USD strengthens against EUR.
- Economic growth: Faster-growing economies attract more foreign investment, strengthening their currency.
- Inflation differentials: A country with higher inflation typically sees its currency weaken (purchasing power parity).
- Geopolitical events: Wars, elections, and trade disputes all move currencies.
- Market sentiment: In times of crisis, "safe haven" currencies (USD, CHF, JPY) typically strengthen.
Central bank intervention
Central banks influence exchange rates through:
- Interest rate policy: Higher rates attract capital inflows, strengthening the currency. This is the most powerful lever.
- Quantitative easing (QE): Central bank buying of government bonds increases money supply, weakening the currency. The ECB's QE programs weakened the EUR during 2015–2022.
- Forward guidance: Communication about future policy moves can move currencies immediately. A single phrase in a Fed chair press conference can move the USD 1%.
- Direct intervention: Central banks can buy/sell their own currency on the open market. This is rare for major currencies but common for managed floats like CNY.
What actually moves rates day-to-day?
For retail users looking at the rate on Toolhub (e.g., USD to EUR), the day-to-day moves are typically driven by:
- Economic data releases: US CPI (inflation), Non-Farm Payrolls (employment), GDP, retail sales. Each can move USD 0.5–1.5% on release day.
- Central bank meetings: FOMC (US), ECB (Eurozone), BoE (UK), BoJ (Japan). Rate decisions and press conferences can move currency 1–3%.
- Geopolitical events: Elections, wars, trade negotiations. Major events can move currency 2–5% in a day.
- Market sentiment: Risk-on / risk-off sentiment drives flows between safe havens (USD, CHF, JPY) and risk assets (AUD, NZD, EM currencies).
- Carry trades: Speculators borrow in low-yielding currencies (JPY, CHF) and invest in high-yielding currencies (AUD, NZD, MXN). When risk appetite shifts, carry trades unwind, causing sharp moves.
Spot vs. forward market
Most consumer currency conversions happen in the spot market — settlement happens T+2 (two business days after the trade). The rate you see on Toolhub is the spot rate.
Businesses with predictable future FX needs can use the forward market — locking in today's rate for settlement in 30, 60, 90, or 180 days. This is called a forward contract and is offered by specialist FX brokers (e.g., Wise Business, XE).
The mid-market rate (recap)
The mid-market rate is the midpoint between the bid (banks buy) and ask (banks sell) prices in the interbank market. It's the "real" exchange rate — the benchmark against which all retail rates are measured.
Banks and remittance services mark up the mid-market rate by 1.5–3% for retail customers. Online-first services like Wise and Revolut offer rates within 0.5% of mid-market. To see the live mid-market rate for any major currency pair, use Toolhub's currency converter.
Conclusion
Exchange rates are determined by supply and demand in the global forex market, driven by trade flows, capital flows, interest rate differentials, central bank policy, and geopolitical events. For pegged currencies, the rate is fixed by central bank policy.
For retail consumers, the practical takeaway is: know the mid-market rate. It's the only honest benchmark. Toolhub shows it live on every currency page — bookmark the pairs you convert most often, and you'll always know whether the rate your bank quotes is fair.