Where the rates and prices come from

Currency rates are the European Central Bank's euro foreign exchange reference rates, served by the Frankfurter API. The ECB publishes them once per business day, at around 16:00 CET. They do not change at weekends or on ECB holidays; the page then shows the last published rate with its date.

They are reference rates, not live market prices: there is no movement during the day, and a bank or card provider trading at the same moment may quote a different figure.

Cross rates. The ECB publishes every currency against the euro only. For any other pair, such as US dollar to Turkish lira, the site divides the two euro rates of the same day (lira per euro ÷ dollars per euro). Both directions of a pair come from the same two published numbers, so the USD/TRY and TRY/USD pages show exact inverses. Results are rounded only for display, and never shown with more significant digits than the ECB rates they come from.

Mid-market values. The figures sit between buying and selling prices. Bank margins, transfer fees and card fees are not included, so the rate you are offered will differ.

Gold and silver prices are spot prices from gold-api.com, in US dollars per troy ounce. The provider uses the codes XAU and XAG, which ISO 4217 defines as one troy ounce of the metal. Each page shows the provider's own update time; it may be when the provider last checked the price rather than the last trade.

In other currencies the US dollar price is multiplied by the ECB reference rate from US dollars to that currency. The two sources update on different schedules, so both dates are shown.

Units. Precious metals are priced per troy ounce (31.1034768 g). The ounce used for food is the avoirdupois ounce (28.349523125 g), which is lighter. The converters on the metal pages also work in grams and kilograms; both ounces are exact definitions.

Spot value is not a shop price.The figures are the theoretical value of pure metal at the spot price. A jeweller's or dealer's buying and selling prices are different: they include the dealer's margin, making charges for jewellery and coins, and taxes where they apply, and jewellery is often an alloy rather than pure metal. The site does not calculate values by purity (karat).

The site has no historical metal prices; metal pages show the current price only.

Historical exchange rates are the same daily ECB reference rates. The comparison table on each currency pair page looks back from 1 month to 10 years; on pages with a chart, the two-dates tool accepts any date from 1999-01-04, the first ECB reference rate.

When a requested date is a weekend or a holiday, the rate of the last business day before it is used, and that day is shown next to the requested one.

On pages with a chart, the line is drawn from a sample of the daily rates:

• 1M: every business day
• 3M: every second business day
• 6M: every third business day
• 1Y: one rate per week
• 3Y: one rate per month
• 5Y: one rate per month
• 10Y: one rate per month

Low and high are the lowest and highest daily reference rates in the period. They can fall on a day the sampled line does not draw, so they can lie slightly outside the line; they are not intraday levels.

A percentage change compares two reference rates. It is not an investment return: it does not account for inflation, interest earned or any fee.

If a figure looks wrong, please open an issue at github.com/mangdasire1/currencyversus/issues. It helps to include the page address, the figure you saw, the figure you expected and where it comes from, and the date and time you looked (with your time zone).

The background texts about currencies and metals show the date they were last reviewed against sources.