A reference exchange rate is not the amount you will receive
Reference conversion helps express an amount in a familiar currency or compare estimates on a common basis. It does not by itself answer “how much will the recipient receive?” That requires the executing provider’s terms.
A rate has a direction and a unit
When one unit of a base currency equals a stated amount of another currency, that number is not the reverse rate. Invert it by division; do not swap the currency labels while retaining the number.
ECB reference rates quote units of other currencies per 1 EUR. To convert between two listed currencies, divide the amount by its source-currency rate per euro and multiply by the destination-currency rate. The euro is an arithmetic bridge here, not a purchase executed by the site.
References: European Central Bank: euro foreign exchange reference rates
Read the rate date, not only when the page was opened
A page opened now can show a reference observed on an earlier day. The observation date describes the rate; retrieval time describes when the system obtained it. Fetching the same record again does not make the rate live.
If a warning says the reference is old, preserve that qualification when copying a comparison into a report. If a currency or the data is unavailable, the correct answer is unavailable conversion, not a guessed rate or an assumed currency peg.
A reference informs; a quote prices a transaction
ECB states that these rates are informational and are not intended for transaction pricing. A calculator result should therefore not be equated with an offer from a bank or transfer provider.
The reference model adds no buy/sell spread, commission or tax. For an actual comparison, read the provider’s amount charged, amount delivered, timing and terms. ToolRoof neither sends money nor locks a rate for a future transaction.
References: European Central Bank: euro foreign exchange reference rates
Two invented teaching rates, not a market quote
Suppose, solely for illustration, that 1 EUR equals 1.20 USD and 0.80 GBP. Converting 120 USD gives 120 ÷ 1.20 × 0.80 = 80 GBP. These are neither current rates nor a historical ECB quotation.
The cross-rate is about 0.6667 GBP per USD, while the reverse is 1.50 USD per GBP. Retain full precision during calculation and round the displayed result. A different transfer-provider quote does not itself establish an error: its rate and fees can differ from the reference assumptions.