Real-time Exchange Rate Calculator By Date

What the Exchange Rate Calculator By Date does

This calculator converts an amount from one currency into another using either the most recent published rate or the rate recorded on a past date you choose. It also shows a full exchange rate table for any base currency, with a search box so you can find a single code or currency name in a long list. It is built for people who need a reference figure: the euro value of an invoice dated last March, the taka equivalent of a dollar salary on payday, or how far a currency has moved since a trip you took last year.

The name says "real-time", so it is worth being precise about what that means here. The rates are daily reference rates published by open data sources, not live prices streamed from a trading desk. The server caches the latest rates for about two minutes and historical rates for a day, so two people looking at the same pair at the same moment see the same number. That makes the tool fast and consistent, but it is not a dealing rate and it will not match what a bank, card network or money changer charges you at the counter.

Where the rates come from

Every conversion and every table row is fetched by our server, not by your browser directly. The server asks two sources in a fixed order:

1. Primary source: the open @fawazahmed0/currency-api dataset served through the jsDelivr CDN. It publishes one file per base currency per day, which is what makes date-based lookups possible.
2. Fallback source: the Frankfurter API (api.frankfurter.app), which republishes reference rates from the European Central Bank. It is only used when the primary source does not answer or returns no data for that base and date.

If neither source has data for the date you picked, the server repeats the request for the latest available rates and the page shows a yellow notice: "Historical data is not available for that date. Latest rate was used as fallback." Read that notice carefully, because the number on screen is then today's rate, not the rate for your date.

Caching, in plain numbers

Because the upstream data itself is published once per day, the two-minute cache does not hide intraday movements; there are none in the source to begin with.

The parts of the screen

Converter panel

• Enter Your Amount: any number from zero upward, with decimals. Negative values are treated as zero.
• Rate type: two options, Today's rate and Pick a date. The date field is disabled until you choose Pick a date.
• Select Your Date: a calendar field. It cannot go past today; a future date sent to the server is replaced with the latest rate.
• Select Your Base Currency and Select Your Target Currency: searchable drop-downs. Type part of a name or code to filter the list. The defaults are USD to EUR.
• Convert Now: runs the conversion. Changing the date, base or target also runs it automatically.

Conversion Result card

The large figure is the converted amount to four decimal places. Under it a chip says Latest or Historical. Three smaller boxes show the Rate (one unit of base expressed in the target, up to six decimals), the Requested Date you asked for, and the Resolved Date, which is the date of the data file the source actually returned. When those two dates differ, the resolved one is the truth.

Exchange Rate Table

Below the converter sits a table with its own Select Your Base Currency drop-down and a Search Currency box. The table lists every currency the source returns for that base, sorted alphabetically by code, each with its rate "Per 1" unit of the base. The footer shows the base, the resolved date and the row count. The table follows the same Rate type and date as the converter, so switching to Pick a date turns it into a historical table for that day.

How to convert an amount on a past date

1. Type the amount in Enter Your Amount, for example 2,500.
2. Under Rate type, choose Pick a date.
3. In Select Your Date, pick the day you care about, such as the invoice date or the day a transfer was booked.
4. Choose the base currency (the one you are converting from) and the target currency (the one you want).
5. Press Convert Now if the result did not already refresh.
6. Check the Resolved Date box and look for the yellow fallback notice before you copy the number anywhere.

To get today's figure instead, switch back to Today's rate. The result and the table both reload.

Using the table for quick comparisons

If you need the value of one currency against many others, the table is quicker than running conversions one by one. Set its base to, say, BDT, then type "dollar" in Search Currency to see every dollar-denominated currency at once, or type a three-letter code like "inr" to jump to a single row. Searching matches both the code and the name, and the search waits a fraction of a second after you stop typing before it asks the server, which keeps the list responsive.

Who finds this useful

• Freelancers and small exporters who invoice in one currency and record income in another, and need the rate for the invoice date rather than today's.
• Bookkeepers reconciling foreign card charges against statements, where the posting date matters.
• Students paying overseas fees who want to see how the cost moved between the offer letter and the payment deadline.
• Travellers who want a sanity check before exchanging cash, knowing that the counter rate will include a margin.
• Writers and researchers who quote a historical price and want to express it in another currency at the time.

Worked example

Suppose a client paid you 1,200 euros on a date last spring and your accounts are kept in US dollars. Set the amount to 1200, choose Pick a date, select the payment date, set the base to EUR and the target to USD. The result card gives the dollar figure, the rate line reads "1 EUR = x USD", and the Resolved Date confirms which day's file was used. If you then switch the table base to EUR, you can see the same day's rate for GBP, CAD or any other currency in one glance, which helps if the client also paid you in another currency that month.

Tips for accurate results

• Always read the Resolved Date. When a source has no file for the day you picked, the server substitutes the latest rate, and the Resolved Date is how you spot it.
• Use the converter for one pair and the table for many. Both use the same source, so they agree for the same base and date.
• For official purposes such as tax filings, check which rate your authority requires. Many tax offices publish their own monthly or annual rates, and those take priority over any calculator.
• If a conversion fails with "Unable to fetch exchange rate right now", wait a minute and try again. It means both sources failed to respond within the server's timeout.
• Rates are shown to six decimals. Round only at the final step if you are multiplying by large amounts.

What not to use it for

• Do not treat the figure as the price you will get from a bank, remittance service or card network. They add a spread and sometimes a fixed fee.
• Do not use it for trading decisions. The data is daily, with no intraday prices, no bid and ask, and no volume.
• Do not assume a figure is historical just because you chose a date. If the fallback notice appears, the number is the latest rate.
• Do not rely on it for legal or contractual conversions unless the contract names this kind of reference rate.

Limitations

• Rates are once-a-day reference values. Nothing on the page updates by the second.
• The page needs our server and at least one of the two upstream sources to be reachable. If both are down, you see an error rather than an old guess.
• The fallback source (Frankfurter, based on European Central Bank data) covers fewer currencies than the primary source, so a rare currency can be missing on days when the fallback is in use.
• The table's base currency must be a three-letter alphabetic code.
• Only one amount is converted at a time; there is no batch upload.

Privacy

The amount, the two currency codes, the date and any search text are sent to our server so it can look up the rate, and the server then requests the matching rate file from the upstream source. No account is needed and the tool does not ask for any personal information. The amount itself is not sent to the upstream source; only the base currency and date are needed to fetch rates.

For a simpler converter without the date picker, see the Currency Rate Converter.

Frequently Asked Questions