Currency Converter
Convert between over 150 currencies with proper rounding rules. Exchange rates update regularly.
Currency Converter
Enter an amount and select a currency β see the value in all others instantly using live exchange rates.
How to use the Currency Converter
You are planning a two-week trip across Europe and need to know how far your Australian dollars stretch. Enter your travel budget β say 5,000 AUD β select Australian Dollar from the dropdown, and instantly see the equivalent in EUR, GBP, CHF, and every other supported currency. Each row has a Copy button for pasting into your budget spreadsheet.
The converter fetches live mid-market rates from the Exchange Rate API on page load and caches them for your session. Converting 100 EUR to JPY, for example, uses the cross-rate formula: 100 x (Rate_JPY / Rate_EUR), which produces approximately 16,400 JPY. A freelancer invoicing a US client 2,000 USD can instantly see that equals roughly 1,832 EUR or 2,700 SGD, helping them decide whether to accept foreign-currency payment.
Real-World Applications & Use Cases
Before a trip, travellers need to understand how far their home currency stretches abroad. Entering your travel budget in your home currency and selecting it from the dropdown instantly shows the equivalent in every destination currency, making it easy to allocate spending across multiple countries on a multi-city itinerary.
Freelancers and remote workers billing clients in foreign currencies need to quote accurate amounts. By entering the invoice total in the client's currency, the converter shows the equivalent in the freelancer's home currency, helping them decide whether to accept foreign-currency payment or negotiate a fixed local-currency rate.
Online shoppers comparing prices across international retailers need a quick way to normalise prices to a single currency. Pasting the listed price into the converter shows the real cost in the shopper's home currency, revealing whether an overseas deal is genuinely cheaper after accounting for exchange rates.
How exchange rate conversion works
Rate source and base currency
The converter uses USD (US Dollar) as its base currency. When the page loads, it fetches the latest rates from the Exchange Rate API (open.er-api.com/v6/latest/USD), which returns a JSON object mapping every supported currency code to its current value relative to 1 USD. These are mid-market indicative rates β the midpoint between bid and ask prices on global currency markets β and are updated daily by the API provider. If the API is unavailable, the tool falls back to a hardcoded set of static rates so the converter remains functional.
Cross-rate calculation formula
Since all rates are expressed relative to USD, converting between any two non-USD currencies requires a cross-rate calculation. To convert from currency A to currency B, the formula is:
Result = Amount x (RateB / RateA)
For example, converting 100 EUR to JPY uses the rates Rate_EUR = 1.0912 (per USD) and Rate_JPY = 149.53 (per USD). The calculation becomes 100 x (149.53 / 1.0912) = 13,703.81 JPY. This two-step routing through USD is standard practice in currency conversion APIs because it avoids maintaining a full matrix of every currency pair β only N rates are needed instead of N-squared.
Rounding and display precision
Most currencies are displayed to two decimal places, matching the smallest unit in circulation (cents, pence, centimes). Currencies without practical sub-units β Japanese Yen (JPY), South Korean Won (KRW), and Indonesian Rupiah (IDR) β are rounded to whole numbers. The toLocaleString method is used for formatting, which applies region-appropriate thousands separators automatically.
Offline fallback and session caching
Once rates are fetched, they are cached in memory and all conversions work without network access for the rest of your session. If the API is unavailable, the tool falls back to a hardcoded set of static rates so you can still perform conversions, though the rates may be outdated. No server-side processing, analytics tracking, or data storage is involved β the tool is a single self-contained Astro page with inline JavaScript.
Frequently Asked Questions
Are the exchange rates accurate?
The rates shown are mid-market indicative rates sourced from a free exchange-rate API. Mid-market rates represent the midpoint between the global bid and ask prices and are suitable for reference, comparison, and educational purposes. They may differ from the rates offered by banks, credit card networks, or money transfer services, which add a spread or commission on top of the mid-market rate.
How often are the rates updated?
Exchange rates are fetched once when the page loads and cached for the duration of your session. The underlying API updates rates daily. For live trading, foreign exchange execution, or time-sensitive international transfers, always verify rates against a real-time financial data provider or your bank's published rates.
Which currencies are supported?
The converter supports 30 major world currencies spanning all continents: USD, EUR, GBP, JPY, AUD, CAD, CHF, CNY, INR, SGD, HKD, NOK, KRW, TRY, RUB, BRL, ZAR, MXN, SEK, NZD, THB, PLN, TWD, IDR, MYR, PHP, CZK, ILS, AED, and SAR. This covers the most commonly traded currencies in global foreign exchange markets.
Why are some values rounded to whole numbers?
Currency display precision is set to match practical usage. Most currencies show two decimal places (cents, pence, centimes), but Japanese Yen, South Korean Won, and Indonesian Rupiah are displayed as whole numbers because their smallest practical sub-unit is rarely used in everyday transactions. The rounding is handled by the toLocaleString method with appropriate maximumFractionDigits settings.
Does this work offline?
Exchange rates require an internet connection on first load to fetch the latest data from the API. Once fetched, the rates are cached in memory and all conversions work offline for the rest of your session. If the API is unavailable, the tool falls back to hardcoded static rates so you can still perform conversions, though the rates may be outdated.
Can I use these rates for actual money transfers?
No. These are indicative mid-market rates intended for reference and comparison only. Actual money transfers involve additional costs including provider margins, wire fees, and intermediary bank charges. Always check the total cost and effective exchange rate offered by your specific bank or transfer service before executing a transaction.
What is the difference between mid-market and retail rates?
The mid-market rate is the theoretical midpoint between the buy and sell prices on global currency exchanges β it is the "true" exchange rate you see on financial news sites. Retail rates, which banks and payment providers offer, include a markup (spread) over the mid-market rate. This spread varies by provider, currency pair, and transaction size, typically ranging from 0.5% to 3%.