What is an exchange rate?
The exchange rate (or FX rate) is the price of one currency expressed in
terms of another. For example, if the USD/BRL rate is 5.00, it means 1 US dollar equals
5 Brazilian reais. Exchange rates fluctuate continuously in international financial
markets, influenced by factors such as central banks' monetary policy, inflation, trade
balance, foreign capital flow and market expectations.
There are two main types of exchange rate:
-
Nominal rate: the direct exchange price between two currencies,
without considering relative purchasing power. It is the value you see on exchange
websites and financial platforms.
-
Real rate: the nominal rate adjusted by the inflation difference
between the two countries. It reflects a currency's real purchasing power relative to
another.
How the base-currency converter works
This tool uses a single base-currency approach, where all rates are
expressed relative to the US Dollar (USD). To convert from any currency A to any
currency B, the calculation performed is:
result = value × (rateB / rateA)
Where rateA and rateB represent how many units of each currency
equal 1 USD. For example, if 1 USD = 5.00 BRL and 1 USD = 0.92 EUR, then to convert 100
BRL to EUR:
100 × (0.92 / 5.00) = 18.40 EUR
This approach is simple, extensible and avoids the need to maintain a separate table for
every possible currency pair.
Why are the rates manual and not updated automatically?
This tool is 100% static — there is no application server, database or
external API calls. All processing happens in the browser itself. This brings
significant advantages:
- Offline operation: the tool works even without an internet connection after the page's initial load.
- No external dependency: it is not subject to request limits, paid API keys or exchange-service outages.
- Suitable for testing: developers can set arbitrary rates to test e-commerce systems, ERPs and other software that performs currency conversions.
The trade-off is that the rates need to be updated manually by the user. For real-time
market quotes, we recommend consulting official services such as the
Central Bank of Brazil (bcb.gov.br), your bank's website or dedicated
financial platforms.
Available currencies and their ISO 4217 codes
The ISO 4217 standard defines three-letter codes to identify currencies
internationally. This is the standard used in banking systems, ERPs and global exchange
platforms. The currencies available in this tool are:
- BRL — Brazilian Real (Brazil)
- USD — US Dollar (United States)
- EUR — Euro (Eurozone)
- GBP — Pound Sterling (United Kingdom)
- JPY — Japanese Yen (Japan)
- ARS — Argentine Peso (Argentina)
- CAD — Canadian Dollar (Canada)
- CHF — Swiss Franc (Switzerland)
- CNY — Renminbi Yuan (China)
- MXN — Mexican Peso (Mexico)
Frequently Asked Questions (FAQ)
Are the displayed rates reliable for real transactions?
No. The rates are illustrative values entered manually as a starting
point. They do not reflect real-time market quotes and may be significantly outdated.
For any real financial transaction — bank exchange, brokerage, international travel or
international transfer — always check the official rates from your bank or a financial
institution authorized by the Central Bank.
How do I update the rates to values closer to reality?
You can edit any rate directly in the fields of the "Exchange rates (editable)" section.
Check a reliable exchange website (such as the Central Bank of Brazil at bcb.gov.br, or
Google Finance) to get the current quote of 1 USD for each currency, and enter the
values in the corresponding fields. Conversions will be recalculated automatically.
Are the rates I edited saved?
Only during the current page session. When you reload, the rates return to the default
illustrative values — so note down or copy the result before leaving, if you need it
later.
Why does the result have so many decimal places?
Dividing exchange rates often results in numbers with many decimal places, especially
for currencies with very different magnitudes relative to each other (such as JPY or ARS
relative to USD). The tool shows up to 4 decimal places for the result and up to 6 for
the rate used, to preserve precision for technical use cases, such as testing financial
rounding systems.
Why does USD show a rate of 1.000000?
The US Dollar is the converter's base currency — all other rates are expressed as "how
many units of this currency equal 1 USD". Therefore, the USD rate is always 1.000000 by
definition and cannot be changed.
Can I use this tool to test e-commerce systems?
Yes, that is one of the main use cases. When developing or testing systems that convert
prices between currencies — online stores, ERPs, international marketplace systems — you
can set arbitrary rates and check your code's behavior. The editable rates let you
simulate extreme scenarios, such as very high rates (ARS) or very small fractional values
(JPY to BRL), to validate rounding, value display and business logic.
What do "bid, ask and mid" exchange rates mean?
In the real foreign exchange market, there are three common prices: the bid
(buy price — what the bank pays for the foreign currency), the ask
(sell price — what the bank charges), and the mid (the midpoint between
bid and ask, used as a reference). This tool uses a single rate (a simplification),
equivalent to the mid rate, without a bank spread. In real transactions, the spread
(difference between bid and ask) is the intermediary's profit.