A currency converter answers a mathematical question: what is an amount worth when multiplied by a reference rate? It does not tell you the amount a bank, card network, cash desk, or transfer service will deliver. Those providers can use a different rate and add a spread or fee. Treat the result as a comparison baseline, not as a transaction quote.
What ToolsFree actually calculates
The converter supports the 39 fiat currencies listed in its selectors. For a source currency, the browser asks the ToolsFree /api/currency endpoint for a dated table from the open-source fawazahmed0/exchange-api project. The proxy tries the jsDelivr copy first and the project's Cloudflare Pages mirror second. The date returned by that dataset is shown beside the result.
The calculation is source amount × reference rate = displayed amount. If an illustrative dataset says that one USD equals 0.92 EUR, then 125 USD × 0.92 equals 115 EUR. The example explains the arithmetic; 0.92 is not presented as today's rate.
Open the currency converter to see the current dataset value and its date.
Reference rate, spread, and fee are different
Reference rate
A reference rate is a common point of comparison. The European Central Bank, for example, publishes euro foreign-exchange reference rates for information purposes and explicitly distinguishes them from transaction rates. ToolsFree uses a separate open dataset, but the same limitation applies: a reference value is not an executable offer.
Spread
The spread is the difference between the reference rate and the rate offered to you. Suppose the reference calculation gives 115 EUR, while a provider offers 111 EUR before a visible fee. The four-euro difference is part of the conversion cost even if the provider advertises a zero fee.
Fixed and intermediary fees
A provider may also deduct a fixed charge. International transfers can involve intermediary or recipient-bank charges that the first screen does not show. Compare the final amount the recipient receives and read the quote terms before confirming.
A repeatable way to compare two offers
- Record the source amount, target currency, reference result, and dataset date.
- Ask each provider for the final target amount after all visible fees.
- Calculate the shortfall: reference result minus final amount received.
- Divide the shortfall by the reference result to compare the effective percentage cost.
- Check whether later intermediary fees, card charges, or cash-withdrawal fees can still apply.
This method compares outcomes without predicting exchange-rate movements or recommending a financial product.
Freshness and failure modes
The upstream project publishes daily datasets rather than live market ticks. ToolsFree may cache an upstream response for one hour, and the browser reuses a successful response for 30 minutes. Weekends, holidays, upstream publication timing, or an outage can make the visible date older than the current day. If no valid table is available, the converter shows an error instead of silently inventing a rate.
For accounting, tax, a contract, or a large transfer, preserve the dataset date and confirm which official or contractual rate your jurisdiction or counterparty requires. ToolsFree provides an informational calculation, not financial advice or a guaranteed settlement amount.