How We Convert Currencies

Guidance last reviewed 2026-08-31

Chart Ding shows your figures in the currency your broker reported them in. That is the number we treat as true, and it never changes.

You can also view those figures in another currency. That is a convenience, not a restatement — a trader in Munich reading a US brokerage statement may simply find euros easier to judge than dollars. This page explains exactly how that view is produced, because a converted number is only as useful as your ability to check it.

This is not a currency converter, and it is not a source of exchange rates. It exists so you can read your own trading results in a currency that is familiar to you. It is not intended to tell you what a currency is worth today, to price a transfer, or to stand in for a bank's or a broker's rate. If you need an exchange rate for anything real, get it from whoever is actually going to give you the money.

The short version


Which rate	European Central Bank daily reference rates, published free
Which date	Each trade uses the rate for its own closing date
Why it differs	Historical rates, not today's; one daily rate, not a live price
What we never do	Convert the total at one rate, or overwrite the native figure
What this is not	Not an exchange-rate service, not an accounting record

Which rate we use

The European Central Bank publishes reference rates for around forty currencies, once per working day, at about 16:00 Central European Time. They are free to use, they go back to 1999, and they are the same rates a European bank would cite.

We fetch that published history and keep a copy in your browser. The date of the most recent rate we hold is shown on screen whenever a converted view is switched on — it appears next to the currency picker, reading something like "EUR at ECB rates to 2026-08-31".

We do not buy a live foreign-exchange feed, and we are not trying to be a dealing screen.

Which date the rate comes from

Every trade is converted using the rate published for that trade's own closing date. A trade closed in March uses March's rate. A trade closed last week uses last week's.

This is the part that surprises people, and it is deliberate. Converting a whole year of results at today's rate would not be a currency conversion — it would apply today's exchange rate backwards over trades that happened when the rate was something else. It would show a gain or a loss that never happened to you, produced entirely by a rate move rather than by anything you did.

Two smaller rules follow from the same principle:

A weekend or holiday walks backwards. Markets close, so some dates have no published rate. We use the most recent working day before the trade, never the one after — a later rate is information that did not exist when the trade closed.
We never average two days. A rate is a published fact on a date. An average of two is a number nobody published.

Why it will not match a currency converter

If you convert your total on Google and compare it to the figure here, the two will differ — sometimes by a noticeable amount. There are two reasons, and both are on purpose.

Each trade uses its own date's rate. Your total is the sum of many conversions at many historical rates, not one conversion of one total at one rate. The more your trades are spread across time, and the more the rate moved during it, the further apart the two answers will be.

The ECB publishes one reference rate per working day. A currency converter shows a live mid-market price that moves continuously. Neither is wrong; they are answers to different questions.

There is a third thing worth saying plainly: what a converted result is actually worth to you depends on when you moved the money, and only you know that. If you traded in dollars and converted to euros in January, your real euro result depends on January's rate, not on the rates of your trade dates. A converted view is an approximation offered for readability. It is not an accounting record.

What this is not

It is worth being blunt about the boundary, because the feature sits close to something it is not.

It is not an exchange-rate service. We do not publish rates, we do not sell them, and the figures here should never be used to decide what a currency is worth or what a transfer should cost. The rate that matters for real money is the one your bank or broker actually gives you on the day, and it will include a spread and fees that a central bank reference rate does not.

It is not an accounting record, and it is not a tax document. Your broker's own statements are the record. Nothing converted here is stored, and switching the view off returns you to exactly the figures your broker reported.

It is a readability feature. That is the whole of it: US markets price in dollars, a great many traders do not think in dollars, and reading your own results in a familiar currency makes them easier to judge.

What we never do

We never overwrite the native figure. Switch the view back and the original numbers are there, unchanged. Nothing converted is ever saved.
We never convert a price. A price belongs to the instrument, not to your account. A UK trader's Apple shares are quoted in dollars whatever currency their account is in, so entry and exit prices are always shown as the market quoted them.
We never add two currencies together. If a statement contains both — Interactive Brokers reports a currency per row, so this is common — the totals that would combine them are not shown at all until you choose a currency to view in. An exchange rate we do not have is not a number we will invent.
We never quietly drop what we could not convert. If any trades fall outside the rates we hold, the count is shown beside the figure, because a total missing some of its trades is not a total.

A note on the exchange rate data

Rates are sourced from the European Central Bank's published euro reference rates. Because every rate is quoted against the euro, a conversion between two other currencies is calculated through it — which is exactly as accurate as any other route through the same published table.

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Nothing on this website is trading or investment advice. Chart Ding is a market clock and alarm tool — it does not recommend trades, evaluate strategies, or take account of anyone's circumstances. Nothing here should be construed as a recommendation or relied on as the basis for a trading decision. Consult a licensed professional before placing real money at risk. Trading involves risk of loss.