Comparing Nominal and Real Rates of Interest

Ask someone what interest rate their fixed deposit is earning, and they will rattle off a number without blinking; 6.5%, 7%, maybe 7.5% if they shopped around. But that number, on its own, tells you very little about whether your money is actually growing. To know that, you need to separate the nominal rate from the real rate, and understand what inflation does to the gap between them.

What is the nominal rate of interest? 🔗

The nominal interest rate is the rate written into your loan agreement, printed on your fixed deposit receipt, or announced by the bank. It tells you how much money you will earn or owe, in rupee terms, without adjusting for the fact that prices in the economy keep rising. If a bank offers a fixed deposit at 7% per annum, that 7% is the nominal rate. It is the “sticker price” of borrowing or lending money.

Nominal rates are useful because they are simple and contractual. Everyone from a bank to a borrower can point to the exact figure and know what is owed. But this simplicity hides a problem: money itself loses value over time because of inflation, and the nominal rate does not account for that loss.

What is the real rate of interest? 🔗

The real interest rate strips out the effect of inflation, showing the actual increase in your purchasing power rather than just the increase in the number of rupees you hold. As the concept is formally defined, the real interest rate is the rate of interest an investor, saver, or lender receives after allowing for inflation. In other words, it measures how much more you can actually buy with your money after a year, not just how much bigger the number in your bank statement has become.

This is the figure that genuinely matters for decision-making. A saver does not care about digits on a passbook; they care about whether their savings can still buy the same basket of groceries, fuel, and services a year later.

The Fisher equation: connecting the two 🔗

Economist Irving Fisher gave us a simple way to link these two ideas. Known as the Fisher equation, it states that the real interest rate is approximately equal to the nominal interest rate minus the inflation rate. Written simply:

Real interest rate ≈ Nominal interest rate − Inflation rate

So if a bank is offering you 7% on a fixed deposit and inflation for the year is running at 5%, your real return is roughly 2%. That 2% is the portion of your return that genuinely adds to your purchasing power; the rest is just compensation for rising prices.

The exact formula versus the quick approximation 🔗

The subtraction method above is an approximation that works well when both the nominal rate and inflation are low. At higher rates, it becomes slightly inaccurate because it ignores the compounding interaction between the two. The more precise version of the Fisher equation states that one plus the nominal rate equals one plus the real rate, multiplied by one plus the inflation rate. For classroom purposes and most everyday calculations, though, the simple subtraction rule gives a fairly reliable estimate, and it is the version most textbooks and bankers use for quick mental math.

Why the distinction actually matters 🔗

Consider two savers. One earns a nominal 10% return during a year when inflation is 8%. The other earns a nominal 6% return during a year when inflation is 2%. On paper, the first saver looks better off, with a higher rate. But their real return is only 2%, identical to what you would get with a naive glance at the second saver’s number, whose real return is 4%, actually double the first. The nominal figure alone is misleading. The real rate reveals who is actually gaining purchasing power and by how much.

This matters for lenders too. If a bank lends money at a fixed nominal rate and inflation turns out to be higher than expected, the lender ends up being repaid in rupees that buy less than anticipated. This is why banks and bond markets watch inflation expectations so closely before setting long-term interest rates.

Nominal and real interest rates in the Indian context 🔗

India’s monetary policy is built almost entirely around this real-versus-nominal distinction. The Reserve Bank of India uses the repo rate, the rate at which it lends to commercial banks, as its primary tool to keep inflation near a target and, by extension, to keep real interest rates in a healthy range for savers and investors.

As of its April 2026 policy review, the Monetary Policy Committee kept the repo rate unchanged at 5.25%, with CPI inflation for 2026-27 projected at around 4.6%. When you run these two figures through the Fisher approximation, the implied real policy rate works out to less than 1%, showing how thin the real cushion can be even when nominal rates look comfortably positive.

How this plays out for ordinary savers 🔗

Bank fixed deposits are the clearest everyday example. When retail inflation runs close to or above a bank’s FD rate, real returns shrink sharply or turn negative. Financial commentary on this has repeatedly flagged the issue; one analysis noted that with retail inflation hovering in the 5-6% range in past years, the real rate of return on bank deposits has stayed negative for extended periods, especially once tax on interest income is factored in. A similar pattern was documented when SBI’s one-year deposit rate of 9% was outpaced by 10% inflation, producing a real return of minus one per cent for depositors.

This is not a rare accident. It is a recurring feature of economies where inflation is volatile. A depositor who only checks the nominal rate before locking in a fixed deposit can be caught off guard, discovering months later that their “safe” investment barely kept pace with rising prices, or lost ground to them.

A quick comparison 🔗

Why this concept sits at the heart of microeconomic distribution 🔗

In the study of income distribution, interest is treated as the reward to capital, just as wages reward labour. But the “reward” only means something once inflation is accounted for. A lender who quotes a high nominal rate during a high-inflation period is not necessarily extracting a higher return; they may simply be protecting themselves from expected price rises. This is exactly why the Fisher equation is taught alongside wage and interest theory: it explains how nominal figures in a contract can disguise the real economic reward being distributed between borrower and lender.

It also explains behaviour you might have noticed already. Banks tend to raise FD and loan rates when inflation expectations rise, and cut them when inflation cools. This is not arbitrary; it is an attempt to keep the real rate somewhere near a stable, acceptable level for both depositors and borrowers, even as the nominal number moves around.

Using the concept in everyday financial decisions 🔗

Whenever you are comparing investment options, whether a fixed deposit, a government savings scheme, or a bond, the nominal rate is only the starting point. The more useful question is: what is the expected inflation rate over the same period, and what real return am I left with once that is subtracted? A 7% FD during 4% inflation leaves you meaningfully better off. The same 7% FD during 7% inflation leaves your purchasing power exactly where it started.

This is also why economists and policymakers watch the real interest rate, not the nominal one, when judging whether monetary policy is genuinely tight or loose. A nominal rate of 6% sounds firm, but if inflation is running at 7%, policy is, in real terms, still accommodative rather than restrictive.

What do you think? The next time you see an advertisement for a fixed deposit or a loan offer, will you look past the nominal rate to estimate the real return first? And if inflation in India were to rise unexpectedly over the coming year, which group do you think would be hurt more: savers holding fixed-rate deposits, or borrowers repaying fixed-rate loans?

References

1. https://en.wikipedia.org/wiki/Real_interest_rate
2. https://en.wikipedia.org/wiki/Fisher_equation
3. https://corporatefinanceinstitute.com/resources/economics/fisher-equation/
4. https://rbi.org.in/Scripts/BS_PressReleaseDisplay.aspx?prid=62514
5. https://outlookindia.com/website/story/business-news-how-fixed-deposits-give-a-negative-rate-of-return/395431
6. https://www.business-standard.com/amp/article/finance/reserve-bank-rate-cut-will-not-hit-depositors-115092901419_1.html