FD Calculator: How Fixed Deposit Maturity, Interest, and TDS Actually Work

A fixed deposit looks simple on paper: you hand a bank money, it hands back more money later. But how much more depends on details most people never check, like how often the interest compounds and whether tax gets deducted before it reaches your account. An fd calculator handles the arithmetic, but it helps to see the mechanics behind it first. This guide uses three real scenarios throughout: ₹1 lakh at 7% for 1 year, ₹5 lakh at 7.3% for 3 years, and ₹10 lakh at 7.5% for 5 years.

How FD Maturity Amount Is Calculated

An fd calculator works off one formula: A = P(1 + r/n)^(nt), where P is your principal, r is the annual interest rate, n is how many times per year the interest compounds, and t is the tenure in years. Indian banks typically compound FD interest quarterly, so n is usually 4.

Take our ₹1 lakh deposit at 7% for 1 year. With quarterly compounding, the maturity amount comes out to ₹1,07,185.90, which means you earn ₹7,185.90 in interest. That's slightly more than a plain 7% of ₹1 lakh (₹7,000), because each quarter's interest starts earning its own interest for the rest of the year.

The gap widens with a longer tenure. On ₹5 lakh at 7.3% for 3 years, quarterly compounding takes the maturity value to ₹6,21,187.96, an interest earning of ₹1,21,187.96. And on ₹10 lakh at 7.5% for 5 years, the maturity amount reaches ₹14,49,948.03, meaning ₹4,49,948.03 in interest on a ₹10 lakh principal.

Notice that the ₹10 lakh deposit doesn't just earn more in absolute terms, it earns proportionally more too, because a longer tenure gives compounding more time to work. The rate your specific bank offers will vary, so run your own numbers through CalcMint's FD calculator rather than relying on these three scenarios alone.

One detail that trips people up: the "t" in the formula doesn't have to be a whole number. Book an FD for 18 months, and t is 1.5, with the formula applying the same way, just with a fractional exponent. Some banks round odd tenures down to the nearest quarter for calculation purposes, so check with the bank on exactly how they compute the maturity date and final interest figure if your deposit doesn't fall on a clean quarter boundary.

The interest rate a bank advertises is also the annual rate, not the rate per compounding period. When the formula divides r by n, it converts that annual rate into a per-quarter (or per-month) rate before applying it repeatedly. That's why two FDs quoting the same annual rate can still mature to different amounts if one compounds quarterly and the other compounds monthly, a point covered later in this guide.

Simple Interest vs Compound Interest FDs

Most bank FDs in India use compound interest, but fd interest calculation works differently under simple interest too, since some post office schemes and older deposit products still use it, and the difference adds up over longer tenures.

Simple interest is calculated only on the original principal, every year, for the life of the deposit. The formula is Interest = P × r × t, with no adjustment for interest already earned. On our ₹1 lakh deposit at 7% for 1 year, simple interest gives exactly ₹7,000, and the maturity amount is ₹1,07,000. Over 1 year, that's barely different from compound interest.

The gap grows once the tenure stretches out. On ₹5 lakh at 7.3% for 3 years, simple interest yields ₹1,09,500 in total interest, against ₹1,21,187.96 under quarterly compounding, a difference of ₹11,687.96 that comes purely from interest earning interest. Stretch it further: on ₹10 lakh at 7.5% for 5 years, simple interest gives ₹3,75,000 in interest, while compound interest gives ₹4,49,948.03, a gap of ₹74,948.03.

That gap is the entire argument for compound interest FDs over simple interest ones, assuming the quoted rate is the same. If a bank ever offers you a choice between the two, or if you're comparing an FD against a scheme that uses simple interest, run both through the maturity formula before assuming the higher headline rate wins. A 7% simple interest product and a 6.8% compound interest product can end up closer than they first appear, depending on the tenure.

Simple interest still shows up in a few corners of Indian personal finance, most commonly in some post office schemes and in older FD products that predate the compound-interest defaults most banks now use. It's also the method used for calculating interest on many personal loans, so if you're used to seeing simple interest quoted on a loan, don't assume the same formula applies automatically to a deposit product without checking.

The practical takeaway is to always check which method a product uses before comparing rates across banks or schemes. A quoted rate on its own tells you nothing about the final number without knowing whether it compounds, and if so, how often. Two products advertising an identical 7.5% rate, one simple and one compounded quarterly, will not return the same amount at maturity, and the gap only grows the longer you hold the deposit.

TDS on FD Interest: When It Applies

TDS, or tax deducted at source, is the portion of your FD interest the bank withholds and pays directly to the government before crediting the rest to you. Understanding the fd interest tds limit matters because it changes how much of your quoted interest you actually receive in hand, which is a common gap people miss when using a tds for fd calculator to estimate returns.

As of FY 2025-26, under Section 194A of the Income Tax Act, banks deduct TDS on FD interest once your total interest from that bank crosses ₹50,000 in a financial year, or ₹1,00,000 if you're a senior citizen aged 60 or above. These thresholds apply per bank, so interest from FDs spread across different banks is tracked separately at each one. The TDS rate is 10% if you've submitted your PAN, and 20% if you haven't.

On our ₹5 lakh deposit at 7.3%, year 1 interest works out to about ₹37,511, which stays under the ₹50,000 threshold, so no TDS applies that year. By year 2, interest on the growing balance rises to roughly ₹40,326, still under the limit. This is a reminder that TDS is assessed year by year on interest actually credited, not on the total interest the FD will eventually earn over its full tenure.

If your total income is below the taxable limit, you can avoid TDS altogether by submitting Form 15G (if you're under 60) or Form 15H (if you're 60 or above) to the bank at the start of the financial year. TDS being deducted doesn't mean your final tax liability is settled either way; it's an advance collection, and your actual tax on FD interest still depends on your income slab, covered in the last section of this guide.

Cumulative FDs raise a specific point of confusion here: even though you don't receive any interest payout until maturity, the bank still calculates and deducts TDS every year on the interest that accrues, not just in the year you finally withdraw the money. So a 5-year cumulative FD can have TDS deducted annually for 5 straight years, each time based on that year's accrued interest crossing the threshold, well before you ever see a rupee of the actual payout. This surprises a lot of first-time FD holders who expect tax to apply only once, at maturity.

If TDS gets deducted but your actual income tax liability turns out to be lower (or zero), you can claim a refund of the excess when you file your income tax return, using Form 16A, the TDS certificate the bank issues each quarter. Keep these certificates on file since matching them against your bank statements makes filing easier, especially if you hold FDs across multiple banks and are tracking several TDS entries at once.

Cumulative vs Non-Cumulative FD

A cumulative fd reinvests your interest back into the deposit instead of paying it out, so the interest itself starts earning interest, and you receive one lump sum, principal plus all accumulated interest, at maturity. A non-cumulative FD does the opposite: it pays out interest at fixed intervals, monthly, quarterly, half-yearly, or annually, while your principal stays untouched until maturity.

The choice comes down to what you need the money for. On our ₹10 lakh, 7.5%, 5-year example, a cumulative FD hands you ₹14,49,948.03 in one go at the end of 5 years. A non-cumulative version of the same FD would instead pay out interest periodically over those 5 years, most likely close to that same ₹4,49,948.03 total interest depending on the payout schedule and rate offered, but as regular income along the way rather than compounding growth.

Retirees or anyone relying on FD interest to cover monthly expenses usually prefer non-cumulative FDs, since the periodic payouts function like a small income stream. Younger investors building toward a specific goal, such as a down payment or an emergency fund, tend to prefer cumulative FDs, since letting the interest compound produces a larger final amount for the same principal and rate. Neither option changes your TDS obligation; both are taxed the same way based on interest credited each year, whether or not that interest is actually paid out to you.

One smaller detail to check when comparing the two: some banks quote a slightly lower effective rate on non-cumulative FDs, since paying out interest periodically instead of letting it compound internally is marginally less profitable for them to offer at the same headline rate. Always compare the actual payout structure and rate on your specific bank's FD page rather than assuming both options produce identical numbers for the same quoted rate. If you're weighing either option against a market-linked alternative for the same goal, our SIP calculator guide walks through that tradeoff.

How Compounding Frequency Changes Returns

FD compounding frequency, meaning how often interest gets added to your principal within a year, has a real effect on your final return, even when the quoted annual rate stays exactly the same. On ₹1 lakh at 7% for 1 year, here's what changes across the common frequencies banks offer:

The difference between annual and monthly compounding on this ₹1 lakh deposit is only ₹229.01 over 1 year, which looks small, but it grows with a larger principal and a longer tenure. Most Indian banks compound FD interest quarterly by default, so when you're comparing FDs across banks, check the compounding frequency along with the headline rate. A bank advertising a slightly lower rate with monthly compounding can sometimes edge out a higher rate compounded only annually, particularly on larger deposits held for several years.

This is also why some banks advertise an "effective annual yield" alongside the nominal rate. The nominal rate is the plain annual figure you see on the FD page; the effective yield already factors in the compounding frequency, so it will always be equal to or slightly higher than the nominal rate. When two banks quote different nominal rates, comparing their effective yields instead gives you a fairer like-for-like comparison, since it accounts for how often each one actually compounds the interest.

On smaller deposits over short tenures, the compounding frequency barely matters, as the ₹229.01 difference above shows. But run the same comparison on ₹10 lakh over 5 years, and the gap between annual and monthly compounding stretches into thousands of rupees, which is enough to factor into your decision when two banks are otherwise offering similar rates.

FAQs

Is TDS deducted on FD interest and at what threshold?

Yes. Under Section 194A, as of FY 2025-26, banks deduct 10% TDS once your total FD interest from that bank crosses ₹50,000 in a financial year (₹1,00,000 for senior citizens aged 60+). Without a PAN on file, the rate rises to 20%. You can avoid TDS by submitting Form 15G or 15H if your total income is below the taxable limit.

What's the difference between cumulative and non-cumulative FD?

A cumulative FD reinvests interest back into the deposit, paying out principal plus all accumulated interest as a lump sum at maturity. A non-cumulative FD pays interest at regular intervals, monthly, quarterly, half-yearly, or annually, while the principal stays untouched. Cumulative FDs suit long-term goals; non-cumulative FDs suit anyone who needs regular income from the deposit.

Can I break an FD before maturity, and what's the penalty?

Most FDs allow premature withdrawal, but the bank typically reduces the interest rate applied, often to the rate applicable for the period the deposit actually stayed open, sometimes with an additional penalty on top. The exact reduction varies by bank and by product, so check your specific FD's terms before assuming a fixed percentage.

How is FD interest taxed — as per your income slab?

Yes. FD interest is added to your total income under "income from other sources" and taxed at your applicable income tax slab rate, regardless of whether TDS was deducted. TDS deducted by the bank is only an advance collection; your actual tax liability depends on your total income and which tax regime you're under, so check the current slab rates that apply to you when filing.

Conclusion

The rate a bank quotes is only part of the picture. Compounding frequency, whether the FD is cumulative or non-cumulative, and TDS thresholds all change what actually lands in your account, sometimes by tens of thousands of rupees on a larger deposit held for several years. Plug in your own principal, rate, and tenure using CalcMint's FD calculator to see your real maturity amount.