What a currency pair actually is

EUR/USD sits at 1.1000 on your screen. Before you can trade that number, you need to know what it is: the cost of one euro, paid in dollars. Everything else in FX builds on that sentence.

Why are currencies quoted in pairs?

A share has a price in money. Money itself doesn't - a pound is worth a pound, which tells you nothing. A currency only has a price relative to another currency, so the market quotes them two at a time. The pair is a ratio, and the number you see is that ratio right now.

That has a consequence people miss for years: there is no such thing as buying a currency on its own. Every FX position swaps one currency for another, so you are always long one and short the other at the same time. "The euro is strong" means nothing until you say what it is strong against.

Which currency is which?

The first currency in the pair is the base, the second is the quote, and the price is always what one unit of the base costs in the quote. GBP/USD at 1.2500: one pound costs 1.2500 dollars. USD/JPY at 125.00: one dollar costs 125.00 yen. The order is market convention, not preference - EUR/USD exists, USD/EUR is not quoted.

Direction follows from that. When the pair rises, the base costs more of the quote - the base strengthened, the quote weakened, in one move. Buying a pair means buying the base and paying with the quote; selling is the reverse. The worked example makes the ratio do some damage.

What this means for you

Every FX position is a relative bet, so name both sides before you form a view - a euro opinion is incomplete until it is a EUR/USD or EUR/GBP opinion. Notice from the worked example that the same rise helped one reader and cost another: direction only means something from a side. And if you hold any currency that is not your own, you already have an FX position, whether you chose one or not. The currency converter below lets you re-run the example with your own numbers and any rate you type.