Currency cross rate

Computes the cross exchange rate between two currencies from their two given rates against a common base currency, and converts an amount.

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amount (number, required) min 0 : The amount, in from_currency, to convert
base_currency (string, required) : Label of the common base currency both rates are quoted against (e.g. "USD")
from_currency (string, required) : Label of the currency the amount is in (e.g. "JPY")
to_currency (string, required) : Label of the currency to convert into (e.g. "GBP")
rate_from (number, required) min 0 : Units of from_currency per 1 unit of base_currency
rate_to (number, required) min 0 : Units of to_currency per 1 unit of base_currency
rate_date (string, ISO date, required) : The date rate_from and rate_to apply to; change it together with the rates to use a different day.
rate_source (string, required) : Citation for where rate_from and rate_to came from; change it together with the rates and rate_date when using a different table.

Both input rates are quoted the same way: units of that currency per 1 unit of the common base_currency.
The visitor supplies rate_from, rate_to, rate_date, and rate_source together; this method never looks up or fetches a rate itself, so any newer official table may be substituted for all four together.
Compute the cross rate (units of to_currency per 1 unit of from_currency): cross_rate = rate_to / rate_from.
Convert the amount: result = amount * cross_rate.
Round result to 2 decimal places.

None.

Cross Rate (Investopedia, 2026-09-30T19:29:48Z) - Standard cross-rate arithmetic: derive the rate between two currencies from their two rates against a shared third (base) currency by dividing. rate_date and rate_source are supplied per use and cite where the two rate values themselves came from.

Name	Inputs	Answer
worked example	`{"amount":10000,"base_currency":"USD","from_currency":"JPY","to_currency":"GBP","rate_from":149.5,"rate_to":0.783,"rate_date":"2026-09-30","rate_source":"Illustrative example rates for cross-rate arithmetic; replace rate_from, rate_to, rate_date, and rate_source with your own dated, cited quotes (for example the ECB euro reference rates page)."}`	52.37 GBP
test vector: USD/EUR to GBP cross	`{"amount":100,"base_currency":"EUR","from_currency":"USD","to_currency":"GBP","rate_from":1.1,"rate_to":0.86,"rate_date":"2026-09-30","rate_source":"Illustrative example rates for cross-rate arithmetic; replace rate_from, rate_to, rate_date, and rate_source with your own dated, cited quotes (for example the ECB euro reference rates page)."}`	78.18 GBP
test vector: identical rates give a 1:1 cross rate	`{"amount":250,"base_currency":"USD","from_currency":"CAD","to_currency":"AUD","rate_from":1.35,"rate_to":1.35,"rate_date":"2026-09-30","rate_source":"Illustrative example rates for cross-rate arithmetic; replace rate_from, rate_to, rate_date, and rate_source with your own dated, cited quotes (for example the ECB euro reference rates page)."}`	250.00 AUD

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Made at: 2026-09-30T22:39:30.722Z
Method sha256: b53c11ca67bc425d64cf1bf46e9efd80fe19aca01dc83f82091c5055ed18ae2a