GLOSSARY
Base currency
The first currency in a pair — the one being priced, and always exactly one unit of it.
By FirstPip editorial team · Updated 2026-09-08 · Educational content · No broker owns this site
Quick answer. The base currency is the first currency listed in a currency pair. It is always one unit, and the exchange rate tells you how much of the quote currency is needed to buy that one unit.
In EUR/USD, the euro is the base currency. In USD/JPY, the US dollar is the base currency. The base is simply whichever currency is written first — and the quantity of it is always fixed at one.
That fixed quantity is the part beginners skip over, and it is the part that makes everything else make sense. The exchange rate never tells you how much a currency is "worth" in the abstract. It answers one narrow question: how much of the other currency does it take to buy one unit of this one?
What does the base currency tell you about a trade?
It tells you what you are actually buying or selling. Position sizes in forex are quoted in units of the base currency, so a standard lot of EUR/USD is 100,000 euros, not 100,000 dollars.
Worked example. You buy one mini lot of EUR/USD — that is 10,000 euros — at a rate of 1.0850:
- You are buying 10,000 units of the base currency (EUR).
- You pay with the quote currency: 10,000 × 1.0850 = $10,850.
- If EUR/USD rises to 1.0950, your 10,000 euros are now worth $10,950 — a $100 gain.
"Going long EUR/USD" and "buying euros with dollars" describe the identical trade. The base currency is the one you end up holding.
Which currency ends up as the base?
Market convention, not logic. There is a loose ordering the market has settled on — EUR is base against everything, then GBP, then AUD and NZD, then USD, then everything else — which is why you see EUR/USD and GBP/USD but USD/JPY and USD/CAD. You do not need to memorise the hierarchy. You only need to read the pair in front of you left to right.
The mistake beginners make
Assuming the base currency is always the US dollar. In EUR/USD and GBP/USD the dollar is the quote, not the base — so a rising chart means the dollar is weakening. In USD/JPY the dollar is the base, so a rising chart means the dollar is strengthening. Traders who do not check which side the dollar sits on end up reading two charts as agreeing when they are actually saying opposite things about the dollar.
Related terms
- Quote Currency — the other half of the pair
- Currency Pair — how the two sides fit together
- Exchange Rate — the number that connects them
- Pip — the unit the rate moves in
Every term above is part of the same idea: how a forex price is written down and what it costs you to trade on it. Start at currency pair if you are reading these for the first time, or browse the full glossary.
Frequently asked questions
What is base vs quote currency?
The base currency is the first currency written in a pair and it is always one unit. The quote currency is the second, and the number tells you how many units of it buy that one unit of the base. In EUR/USD 1.1598, one euro is the thing being priced and 1.1598 US dollars is the price.
Why is USD a base currency?
For most currencies it is, but not for all — and that is a publishing convention, not a ranking. The Federal Reserve's H.10 table is headed "Rates in currency units per U.S. dollar except as noted by an asterisk", so in most rows the dollar is the base. In the four starred rows of the release dated 31 August 2026 — the Australian dollar, the euro, the New Zealand dollar and the pound — the footnote reads "U.S. dollars per currency unit", which makes the dollar the quote currency instead.
Is base currency domestic or foreign?
Neither. It is whichever currency the publisher decided to put first. The European Central Bank heads its daily table "All currencies quoted against the euro (base currency)", so at the ECB the euro is always the base. The Fed publishes both directions inside one table. The same currency can be the base in one place and the quote in another: the ECB quotes EUR/GBP, while the Fed's starred sterling row prices the pound in dollars.
What are the 8 major currencies in forex?
No regulator or central bank publishes an official list of "majors" — the term is market convention, which is why different websites give you six, seven or eight. What is measured is how much each currency is actually traded: the BIS Triennial Survey for April 2025 found the US dollar on one side of about 89% of all trades, the euro 28.9%, the yen 16.8% and sterling 10.2%. Those shares add to 200% because every trade involves two currencies.
How do you tell which currency is the base?
Read it off the notation, never off which currency matters to you. Where a pair is written with a slash, the base is the one before it. Where there is no pair notation — as in the Fed's H.10 table — you have to read the stated direction of the units instead: "yen per US dollar" makes the dollar the base, "US dollars per euro" makes the euro the base.