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In a currency pair such as USD/JPY, the first currency is the base currency and the second is the quote currency. A quote of 150 means 150 Japanese yen per US dollar: it prices one unit of the base currency in units of the quote currency. Read the units before you calculate an amount or interpret a change.
All rates and amounts below are fictional teaching examples. They are positive, common indicative mid rates, not live prices or offers to exchange money.
Start with one unit of the base currency
The pair label A/B follows the base/quote convention: A comes first and B comes second. The numerical rate r means r units of B for one unit of A. The quote currency is also called the counter currency. IG Academy explains this first/second currency convention in its introduction to forex trading. [1]
Keep the pair label separate from the units of its number. The label USD/JPY puts USD first, while its rate is measured in JPY per USD. Writing “150 JPY per USD” makes the meaning harder to reverse accidentally.
“Base” here identifies the first currency in that pair. It does not automatically mean the reserve currency, your account currency, your funding currency or the currency used for settlement.
Multiply or divide using the units
To express a base-currency amount in the quote currency, multiply by the rate. To express a quote-currency amount in the base currency, divide by that same rate. You can check the direction by cancelling the units.
| Pair label | Base / quote | Rate and meaning | Base to quote | Quote to base |
|---|---|---|---|---|
| USD/JPY | USD / JPY | 150 JPY per USD; 1 USD = 150 JPY | 100 USD × 150 JPY/USD = 15,000 JPY | 15,000 JPY ÷ 150 JPY/USD = 100 USD |
| EUR/USD | EUR / USD | 1.20 USD per EUR; 1 EUR = 1.20 USD | 100 EUR × 1.20 USD/EUR = 120 USD | 120 USD ÷ 1.20 USD/EUR = 100 EUR |
In the first multiplication, USD cancels and leaves JPY. In the second example, EUR cancels and leaves USD. Division reverses each calculation under the same assumed rate. These are mathematical identities, not an executed round trip or a promise that real conversions have no costs.
Reverse the units by taking the reciprocal
For one positive common quote, reversing the currencies gives 1 divided by the original rate. If 1 USD corresponds to 150 JPY, then 1 JPY corresponds to 1/150 USD. The reversed pair label is JPY/USD, and its rate is measured in USD per JPY.
A higher USD/JPY number means one dollar is worth more yen under that quotation. If the fictional rate rises from 150 to 156 JPY per USD, the dollar has risen relative to the yen. In the reverse orientation, one yen is worth fewer dollars. Neither statement ranks the currency against every other currency or measures its purchasing power against everything.
Why +4% does not reverse to −4%
A percentage change divides the difference by the starting value in the orientation you are reading. Reversing the quote changes that starting value.
| Pair label and rate units | T0 → T1 | Proportional change | Percentage change |
|---|---|---|---|
| USD/JPY; JPY per USD | 150 → 156 | 156/150 − 1 = 1/25 | +4% |
| JPY/USD; USD per JPY | 1/150 → 1/156 | (1/156)/(1/150) − 1 = −1/26 | −50/13% ≈ −3.846% |
For the original quote, the increase is 6 divided by 150, or 0.04. For the reciprocal, the proportional change is 150/156 − 1 = −1/26. Multiplying that ratio by 100 gives −50/13%, or −3.846153846…%. The ratio −1/26 is not −1/26%, and the reciprocal percentage change is not −4%.
This compares two ways to express the same fictional rate move. It does not calculate a portfolio return: you would also need to know the position, product and costs.
Record what the quote tells you—and what it leaves open
Before comparing rates, put the source, observation time, quote kind and units beside them. In this example those fields are assumptions, so the record should say so.
| Field | Recorded here | What remains unknown |
|---|---|---|
| Source, time and quote kind | Invented common mid-rate observations T0 and T1 | No real provider, date or market feed |
| Pair and units | USD/JPY: 150 then 156 JPY per USD; reciprocal: USD per JPY | No explanation of what caused the move |
| Conversion and product | Amounts calculated at the stated common rate | Customer-executable amount, costs and product rights |
| Service and eligibility | Educational quotation example | Availability of a particular product or your eligibility to use it |
A displayed indicative or mid rate alone does not establish the amount a customer can actually exchange. The pair notation also does not tell you whether a product gives you currency ownership or derivative exposure, what it costs, or how it settles. For those distinctions, read the actual product terms alongside our guide to investing, trading and speculation.
Explaining a news-driven move is a separate task. A change after a policy announcement or jobs release does not, by itself, identify its cause or guarantee the next direction. Our guides to CME FedWatch probabilities and US nonfarm payrolls explain those inputs without turning them into a fixed currency forecast.
Questions about base and quote currency
Which is the base currency in USD/JPY?
USD is the base currency; JPY is the quote currency. A number of 150 means 150 JPY per 1 USD in our fictional example.
Does a higher USD/JPY quote mean the yen rose against the dollar?
No. It means one dollar corresponds to more yen under that quotation. The yen’s value in dollars moves in the opposite direction.
Is the inverse pair’s percentage change exactly the negative?
No. Each orientation uses its own starting denominator. In the example, +4% in USD/JPY corresponds to about −3.846% in the reciprocal quotation.
Can you exchange money at a displayed mid rate?
The displayed number alone does not establish that. You need the actual conversion quote and its conditions to know the amount and costs.
Does the pair tell you what product you own?
No. A pair label describes the currencies being quoted. It does not establish currency ownership, derivative rights, settlement terms, profitability or eligibility to use a service.
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Sources and scope
- IG Academy: Introduction to forex trading — the “Base versus quote currencies” section supports the first/second currency convention. IG is a broker; its educational explanation is not an eligibility or legal determination.
The examples and arithmetic are original and fictional. The saved IG text extract was checked on 19 October 2026; that is an evidence-check date, not its publication date. No live exchange rates are used.
HypaForecast publishes educational guides and operates a prediction-market service. This guide does not establish that HypaForecast offers FX, CFDs or perpetuals, or that you are eligible to use a service.
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