.er-calc-container {
max-width: 800px;
margin: 20px auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
background: #fff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.er-calc-header {
background: #0056b3;
color: white;
padding: 20px;
border-radius: 8px 8px 0 0;
text-align: center;
}
.er-calc-header h2 {
margin: 0;
font-size: 24px;
}
.er-calc-body {
padding: 30px;
display: flex;
flex-wrap: wrap;
gap: 20px;
}
.er-input-group {
flex: 1 1 300px;
display: flex;
flex-direction: column;
}
.er-input-group label {
font-weight: 600;
margin-bottom: 8px;
font-size: 14px;
color: #444;
}
.er-input-group input {
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.er-input-group input:focus {
border-color: #0056b3;
outline: none;
box-shadow: 0 0 0 3px rgba(0,86,179,0.1);
}
.er-hint {
font-size: 12px;
color: #666;
margin-top: 4px;
}
.er-calc-actions {
width: 100%;
margin-top: 10px;
text-align: center;
}
.er-calc-btn {
background: #28a745;
color: white;
border: none;
padding: 15px 40px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.2s;
}
.er-calc-btn:hover {
background: #218838;
}
.er-results {
width: 100%;
margin-top: 30px;
background: #f8f9fa;
padding: 20px;
border-radius: 4px;
border-left: 5px solid #0056b3;
display: none;
}
.er-result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #e9ecef;
}
.er-result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.er-result-label {
font-weight: 500;
color: #555;
}
.er-result-value {
font-weight: 700;
font-size: 18px;
color: #333;
}
.er-final-value {
color: #0056b3;
font-size: 24px;
}
.er-article {
max-width: 800px;
margin: 40px auto;
padding: 0 20px;
line-height: 1.6;
color: #222;
}
.er-article h2 {
color: #0056b3;
margin-top: 30px;
}
.er-article h3 {
color: #333;
margin-top: 25px;
}
.er-article ul {
margin-left: 20px;
}
.er-article li {
margin-bottom: 10px;
}
.er-formula-box {
background: #f1f8ff;
padding: 15px;
border-radius: 4px;
font-family: monospace;
margin: 15px 0;
border: 1px solid #cce5ff;
}
function calculateCurrency() {
// 1. Get Input Values
var amountInput = document.getElementById('er_amount').value;
var rateInput = document.getElementById('er_rate').value;
var feePctInput = document.getElementById('er_fee_pct').value;
var feeFlatInput = document.getElementById('er_fee_flat').value;
// 2. Parse Float and Handle Defaults
var amount = parseFloat(amountInput);
var rate = parseFloat(rateInput);
var feePct = parseFloat(feePctInput);
var feeFlat = parseFloat(feeFlatInput);
// 3. Validation
if (isNaN(amount) || amount <= 0) {
alert("Please enter a valid Amount to Send.");
return;
}
if (isNaN(rate) || rate <= 0) {
alert("Please enter a valid Exchange Rate.");
return;
}
if (isNaN(feePct)) feePct = 0;
if (isNaN(feeFlat)) feeFlat = 0;
// 4. Calculation Logic
// Calculate the variable fee based on the percentage of the total amount
var variableFee = amount * (feePct / 100);
// Total fees in source currency
var totalFees = variableFee + feeFlat;
// Amount remaining to be converted after fees are deducted
var amountToConvert = amount – totalFees;
// Handle case where fees exceed amount
if (amountToConvert 0) {
effectiveRate = finalTargetAmount / amount;
}
// 5. Update UI
document.getElementById('display_fees').innerText = totalFees.toFixed(2);
document.getElementById('display_converted_principal').innerText = amountToConvert.toFixed(2);
document.getElementById('display_rate').innerText = rate.toFixed(4);
document.getElementById('display_final_target').innerText = finalTargetAmount.toFixed(2);
document.getElementById('display_effective_rate').innerText = effectiveRate.toFixed(4);
// Show results
document.getElementById('er_results_area').style.display = 'block';
}
Exchange Rates: How to Calculate Currency Conversions Manually
Calculating exchange rates involves more than just multiplying one number by another. To understand exactly how much money a recipient will receive—or how much a foreign transaction will cost you—you must account for the interbank rate, the spread (the bank's markup), and any transfer fees. This guide explains the mathematics behind currency exchange.
The Basic Exchange Formula
At its core, converting currency requires a multiplication of the Source Amount by the Exchange Rate. If you possess Currency A and want to buy Currency B, the formula is:
Result = Amount (Currency A) × Rate (A to B)
Example: You want to convert 1,000 USD to EUR. The rate is 1 USD = 0.85 EUR.
- Calculation: 1,000 × 0.85 = 850 EUR.
Accounting for Fees and Commissions
Banks and exchange bureaus rarely trade at the pure "mid-market" rate. They make money by charging fees. There are two primary ways these costs are calculated:
1. The Spread (Markup)
Instead of the real rate (e.g., 0.85), the bank gives you a "Buy" rate (e.g., 0.82). The difference is their profit. In this scenario, you simply use the lower rate in the basic formula.
Math: 1,000 × 0.82 = 820 EUR (You effectively lost 30 EUR to the spread).
2. Upfront Fees (Flat or Percentage)
Many providers charge a separate service fee. Usually, this fee is deducted from the amount before conversion. This drastically changes the calculation:
Step 1: Net Amount = Total Amount – (Fixed Fee + % Commission)
Step 2: Final Amount = Net Amount × Exchange Rate
Example with Fees:
- Send Amount: 1,000 USD
- Rate: 0.85
- Fixed Fee: 10 USD
- Commission: 2%
Calculation:
- Calculate % Commission: 1,000 × 0.02 = 20 USD.
- Total Fees: 10 (fixed) + 20 (commission) = 30 USD.
- Net Amount to Convert: 1,000 – 30 = 970 USD.
- Convert: 970 × 0.85 = 824.50 EUR.
Calculating the "Effective" Exchange Rate
To compare different providers who have confusing combinations of rates and fees, you should calculate the Effective Exchange Rate. This tells you the true cost of the transfer.
Effective Rate = Final Amount Received / Total Amount Sent
Using the example above: 824.50 EUR / 1,000 USD = 0.8245.
Even though the advertised rate was 0.85, your effective rate was 0.8245. Always look for the highest effective rate when sending money.
Common Definitions
- Source Currency: The money you currently hold (e.g., USD, GBP).
- Target Currency: The money you want to acquire (e.g., EUR, JPY).
- Mid-Market Rate: The "real" rate banks use to trade with each other. Consumers rarely get this rate without a markup.
- Cross Rate: An exchange rate between two currencies computed by reference to a third currency (usually the US dollar).