A cross rate in foreign exchange (forex) refers to the exchange rate between two currencies that are not the US dollar (USD). Most currency pairs are quoted against the USD (e.g., EUR/USD, GBP/USD, USD/JPY). However, when you need to exchange one non-USD currency for another (e.g., EUR to JPY), you're dealing with a cross rate. Since direct trading pairs for all currencies don't always exist or might be less liquid, cross rates are typically derived using a common third currency, usually the USD, as an intermediary.
function calculateCrossRate() {
var currency1 = document.getElementById("currency1").value.trim().toUpperCase();
var amount1 = parseFloat(document.getElementById("amount1").value);
var rate1 = parseFloat(document.getElementById("rate1").value);
var currency2 = document.getElementById("currency2").value.trim().toUpperCase();
var rate2 = parseFloat(document.getElementById("rate2").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(amount1) || isNaN(rate1) || isNaN(rate2) || currency1 === "" || currency2 === "") {
resultDiv.innerHTML = "Please enter valid inputs for all fields.";
return;
}
// Logic to derive cross rate:
// If rate1 is "1 USD = X Currency1", then 1 Currency1 = 1/X USD.
// If rate2 is "1 USD = Y Currency2", then 1 Currency2 = 1/Y USD.
// To find the rate between Currency1 and Currency2 (e.g., Currency1/Currency2), we can use USD as the intermediary:
// (Currency1 / USD) * (USD / Currency2) = Currency1 / Currency2
// We have:
// 1 Currency1 = (1 / rate1) USD
// 1 USD = rate2 Currency2
// So, 1 Currency1 = (1 / rate1) USD = (1 / rate1) * (rate2 Currency2) = (rate2 / rate1) Currency2
// This gives us the rate of Currency1 in terms of Currency2.
// Convert amount1 to USD first
var amountInUSD = amount1 / rate1;
// Convert USD amount to currency2
var amountInCurrency2 = amountInUSD * rate2;
// Calculate the direct cross rate (1 Currency1 = ? Currency2)
var crossRate = rate2 / rate1;
resultDiv.innerHTML =
"Calculation Breakdown:" +
"1. Convert " + currency1 + " to USD:" +
"" + amount1 + " " + currency1 + " / " + rate1 + " (" + currency1 + "/USD) = " + amountInUSD.toFixed(4) + " USD" +
"2. Convert USD to " + currency2 + ":" +
"" + amountInUSD.toFixed(4) + " USD * " + rate2 + " (" + currency2 + "/USD) = " + amountInCurrency2.toFixed(2) + " " + currency2 + "" +
"Result:" +
"The exchange rate is approximately 1 " + currency1 + " = " + crossRate.toFixed(4) + " " + currency2 + "." +
"Therefore, " + amount1 + " " + currency1 + " is equal to approximately " + amountInCurrency2.toFixed(2) + " " + currency2 + ".";
}
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