What an exchange rate is

An exchange rate looks like one number and is really a ratio with two sides. Most confusion about currencies starts there.

It is a price, and prices have two sides

An exchange rate is the price of one currency in terms of another. That makes it unlike almost every other number in this course, because it has no independent existence — it is always a comparison.

India quotes it the usual way for most of the world: rupees per unit of foreign currency. So "the rupee is at 90" means ninety rupees buys one dollar.

Which produces the single most common confusion in reading currency news. When that number rises, the rupee has become weaker, because you now need more rupees for the same dollar. A rising exchange rate is a falling currency. The number and the thing it describes move in opposite directions, and headlines routinely get this wrong in both directions.

The reciprocal would avoid the problem — dollars per rupee — and nobody uses it, so the habit to form is simply: higher number, weaker rupee.

Weaker is not worse

The second confusion is moral rather than arithmetic. A falling currency gets written about as a national failure, and it is not a verdict on anything.

A weaker rupee means:

Exporters receive more rupees for the same dollar of sales. An Indian software firm billing in dollars has a better quarter without selling anything extra.

Imports cost more rupees. Crude oil, electronics, edible oil, gold, machinery. India imports a great deal, so this reaches ordinary prices quickly.

Foreign debt gets heavier. A company that borrowed dollars repays them with more rupees, which is why chapter 12 of the company analysis subject called a yen-denominated loan a currency risk rather than only a cheap rate.

Foreign travel and education get dearer, in the most direct way most households experience.

So a currency move redistributes between groups within the country rather than making the country uniformly better or worse off. The question is never "is the rupee weak" but "weak against what, how fast, and who holds the exposure".

The speed matters more than the level, and that is the thing policy actually cares about. An economy can adjust to almost any exchange rate given time. A disorderly move in a fortnight is what breaks contracts and balance sheets, and chapter 6 is a case study in exactly that distinction.

Nominal, real and effective

Three refinements, in increasing order of usefulness and decreasing order of fame.

The nominal bilateral rate is the headline: rupees per dollar. It says nothing about what either currency buys at home.

The real rate adjusts for inflation in the two countries. If India's prices rise 6% a year and America's rise 2%, then a nominal rupee that is flat against the dollar is actually getting more expensive in real terms — Indian goods are becoming dearer relative to American ones even though the screen has not moved. This is the same correction chapter 6 of the inflation subject applied to a savings rate, in a different setting.

The effective rate recognises that the dollar is not the only thing India trades with. A nominal effective exchange rate is the rupee against a basket of trading partners' currencies, weighted by how much trade is done with each. The real effective exchange rate does that and adjusts for relative inflation.

Why this matters practically: the rupee can fall against the dollar while rising against everything else. If the dollar is strengthening globally, every currency falls against it, and a rupee that falls less than the euro and the yen has actually become more expensive for European and Japanese buyers. The headline says "rupee weakens" and Indian exporters to Europe have just become less competitive.

So when a currency move is being explained, the first question is whether it is a rupee story or a dollar story. Very often it is a dollar story and the rupee is a bystander.

Who publishes the official number

There is no single price. Thousands of transactions happen at slightly different rates every second, so somebody has to compute a benchmark.

In India that is Financial Benchmarks India Private Limited, which computes and publishes foreign exchange reference rates against the rupee on every Mumbai business day. It has covered USD, EUR, GBP and JPY since 10th July 2018, and the suite was extended on 5th January 2026 to include AED and IDR — the latter two reflecting where Indian trade and remittances actually go.

Two things follow.

The reference rate is a benchmark, not a price you can get. It exists so that contracts, valuations and accounts have a common number to settle against. Your bank's rate for buying dollars will be worse, and the exercise at the top of this chapter is to find out by how much.

A benchmark is a published methodology, not an opinion. FBIL computes the USD/INR rate from transaction data within a defined window, by a method it publishes. That is the same principle this course met in the CPI basket and the GDP deflator: the number is the output of a stated procedure, and the procedure is the thing to read when the number surprises you.

What the rest of the subject is for

An exchange rate is a price, and prices move because of what people do at them. The rest of this subject is the ledger that records every one of those transactions — the balance of payments — because you cannot explain a currency without knowing what is flowing in and out and why.

Chapter 2 sets up the accounting, which turns out to be an identity rather than a measurement. Chapters 3 and 4 take the two halves apart on India's actual figures. Chapter 5 asks what moves the rate. Chapter 6 reads a real intervention from the documents the Reserve Bank published at the time.

The point

An exchange rate is the price of one currency in another, quoted in India as rupees per dollar — so a rising number is a weakening rupee. Weaker is not worse: it helps exporters, raises import costs, and makes foreign debt heavier, so it redistributes rather than damages, and the speed matters more than the level. The bilateral rate is only half the story, because a rupee can fall against the dollar while rising against everything else. The official reference rate is published by FBIL on every Mumbai business day, and it is a benchmark rather than a price you will be offered.