Currency Calculator

What this currency calculator does

This calculator converts an amount from one currency to another using an exchange rate you provide. It shows both directions: how much the amount is worth in the second currency, and how much of the first currency the same amount would represent at the same rate.

It does not download a live rate. Exchange rates move constantly and depend on the market, the provider, and the size of the transaction, so a rate you enter yourself is often more useful for planning than a stale cached quote.

How to use this calculator

1. Enter the amount you want to convert.
2. Enter the exchange rate: the number of second-currency units that one first-currency unit buys.
3. Optionally rename the two currencies so the result is easier to read.
4. Click Calculate to see the forward and reverse conversions.

The default example uses an amount of 100 and a rate of 4. The forward result is 400 and the reverse result is 25.

Currency conversion formulas

Forward: Amount in currency B = Amount in currency A × Rate
Reverse: Amount in currency A = Amount in currency B ÷ Rate

If one unit of currency A buys 4 units of currency B, then 100 units of A buy 400 units of B. To go the other way, divide by 4: 100 units of B buy 25 units of A.

What the results mean

• Forward: the amount converted from currency A to currency B.
• Reverse: the amount of currency A that the same numeric amount of currency B would buy at the same rate.
• Exchange rate: the bridge between the two currencies. The labels do not change the arithmetic; they only make the output readable.

The rate is a single number. It does not include a bank spread, a card fee, a transfer fee, or a markup. Those costs can make the effective rate worse than the market rate.

Assumptions and limitations

This calculator assumes a constant rate and no transaction costs. It does not fetch live rates, store historical rates, or identify currencies by ISO code. It does not model bid/ask spreads, bank fees, rounding rules, or limits on cash transactions.

The result is an arithmetic conversion, not a quote. If you are sending money, check the provider's rate and fees at the moment of the transaction. If you are accounting for a past transaction, use the rate that applied on the transaction date and follow the accounting rules for your situation.

Frequently asked questions

Which exchange rate should I enter?

Use the rate that matches your purpose. For a card purchase, the card network's rate after any markup is usually the relevant one. For planning, a recent market rate is a reasonable starting point. For accounting, use the rate required by the applicable rules.

Why is the reverse conversion not just the same number?

A rate of 4 means one unit of A buys 4 units of B. Going backward, one unit of B buys one quarter of a unit of A. The reverse conversion divides by the rate; it does not multiply by it.

Does the calculator include fees?

No. It converts the amount at the rate you enter. Bank fees, card foreign-transaction fees, and transfer markups are separate and can raise the effective cost of the conversion.

Can I use real currency names?

Yes. Rename the two labels to the currencies you are comparing, such as USD and EUR. The labels are display text; they do not change the rate or validate the currency pair.

Source

References:

• Federal Reserve — Foreign exchange rates (H.10)
• European Central Bank — Euro reference exchange rates

Disclaimer

This calculator is for informational and educational purposes only. It is not a live exchange-rate quote, a wire instruction, or financial advice. Exchange rates change continuously and providers apply their own spreads and fees. Confirm the rate and total cost with your bank or payment provider before transacting.