FD Calculator — Calculate Fixed Deposit Maturity Amount & Interest

By sadiqbd · June 6, 2026

The interest rate on the brochure isn't the whole story

Banks advertise FD rates prominently — 7%, 7.5%, 8% — and most people take the number at face value. What they don't always account for is how compounding frequency and tenure interact with that rate to produce the actual maturity amount. Two FDs with the same headline rate can give meaningfully different returns depending on whether interest compounds annually, quarterly, or at maturity.

An FD calculator cuts through this. You put in the principal, the rate, the tenure, and the compounding frequency — and it tells you exactly what you'll walk away with. No surprises at maturity.

How Fixed Deposit Interest Works

A fixed deposit earns interest on a lump sum over a fixed period. Unlike a savings account where you can deposit and withdraw freely, an FD locks your money in for the agreed tenure. In return, it usually offers a higher and guaranteed interest rate.

The maturity amount depends on whether the bank compounds interest or pays it out periodically:

Compound interest FD (most common for cumulative FDs):

A = P × (1 + r/n)^(n×t)

Where:

A = maturity amount
P = principal
r = annual interest rate (as a decimal)
n = compounding frequency per year (quarterly = 4, monthly = 12, annually = 1)
t = tenure in years

For a ৳1,00,000 FD at 7.5% compounded quarterly for 3 years:

A = 1,00,000 × (1 + 0.075/4)^(4×3) = 1,00,000 × (1.01875)^12 ≈ ৳1,25,023

Total interest earned: ৳25,023.

Simple interest FD (less common, sometimes used for short tenures):

A = P × (1 + r × t)

For the same inputs: A = 1,00,000 × (1 + 0.075 × 3) = ৳1,22,500

The difference — ৳2,523 — comes entirely from compounding. Over longer tenures with larger principals, this gap grows substantially.

How to Use the FD Calculator on sadiqbd.com

Enter the principal amount — the amount you're depositing. This is your starting investment.
Enter the annual interest rate — use the rate your bank is offering. Check whether it's a special rate (for senior citizens, for instance) or the standard rate.
Select the tenure — in years, months, or both. Many banks allow fractional tenures like 1 year 6 months.
Choose the compounding frequency — quarterly is standard for most Indian and Bangladeshi bank FDs. If you're unsure, quarterly is a safe default.
Read the result — you'll see the maturity amount and the total interest earned broken out separately.

Run multiple scenarios side by side to compare how a longer tenure or a marginally better rate changes your outcome.

Real-World Examples

Building an emergency fund

Shabnam has ৳2,00,000 she wants to keep accessible but earning more than a savings account. She books a 1-year FD at 6.75% compounded quarterly.

A = 2,00,000 × (1 + 0.0675/4)^4 ≈ ৳2,13,884

Interest earned: ৳13,884 in 12 months — risk-free and guaranteed. More than double what a typical savings account would give her.

Comparing two bank offers

Tariq has ৳5,00,000 to invest for 2 years. Bank A offers 7.25% compounded annually; Bank B offers 7% compounded quarterly.

Bank A: 5,00,000 × (1.0725)^2 ≈ ৳5,75,256 → interest: ৳75,256
Bank B: 5,00,000 × (1 + 0.07/4)^8 ≈ ৳5,72,441 → interest: ৳72,441

Bank A wins despite the more frequent compounding at Bank B — the 0.25% rate advantage more than compensates. This is the kind of comparison that takes two minutes in a calculator and one wrong guess without one.

Long-term wealth building with FD laddering

Rumana invests ৳3,00,000 in a 5-year FD at 8% compounded quarterly.

A = 3,00,000 × (1 + 0.08/4)^20 ≈ ৳4,45,731

Her money grows by nearly 49% without any active management. She also sets up a second FD of ৳1,00,000 maturing every year (an "FD ladder") so she always has liquidity without breaking the longer-term deposit.

What Affects Your FD Returns

Interest rate is the most obvious factor. Even a 0.5% difference compounds meaningfully over 3–5 years. Senior citizen rates (often 0.25%–0.5% higher) are worth checking if you're eligible.

Tenure has a non-linear effect because of compounding. A 5-year FD doesn't just earn twice as much as a 2.5-year one — it earns more, because interest compounds on top of itself for longer. Longer isn't always better (you lose liquidity), but the maturity amount jump is real.

Compounding frequency matters, though less than most people think for standard tenures. Monthly compounding vs. quarterly compounding on a ৳1 lakh 3-year FD at 7.5% produces a difference of roughly ৳400. Not nothing, but not a deciding factor.

Tax on interest isn't included in the calculator but affects your net return. FD interest is taxable income in most jurisdictions. If you're in a higher tax bracket, your effective post-tax yield is lower than the nominal rate — worth accounting for when comparing FDs to other instruments.

Tips for Getting the Most From Your FD

Don't ignore special tenure rates. Banks sometimes offer higher rates for odd tenures like 399 days or 555 days. These aren't marketing gimmicks — they're genuine rate bumps. Check your bank's rate card for these before defaulting to a round-number tenure.

Reinvest at maturity rather than taking payout. Auto-renewal at maturity keeps the compounding going without a gap. If you take out the interest and redeposit the principal, you lose the compounding benefit on the interest already earned.

Use the calculator to plan premature withdrawal impact. Most FDs charge a penalty (typically 0.5%–1% rate reduction) for early withdrawal. If you might need the money before maturity, calculate both the expected maturity amount and the penalised amount to understand your worst case.

For large deposits, split across banks. Deposit insurance in Bangladesh covers up to ৳1,00,000 per depositor per bank under BDIFS. If you're investing ৳10 lakh+, spreading across multiple banks gives you full coverage. The FD calculator helps you project maturity amounts for each deposit separately.

Compare FD returns against other options. Use the Compound Interest Calculator alongside the FD Calculator to compare how the same principal might grow in a different instrument at a different compounding schedule.

Frequently Asked Questions

What's the difference between cumulative and non-cumulative FDs? In a cumulative FD, interest compounds and is paid out at maturity along with the principal. In a non-cumulative FD, interest is paid out at regular intervals (monthly, quarterly, annually) and only the principal comes back at maturity. The FD calculator covers cumulative (compound interest) FDs — what most people mean when they say "FD."

Is FD interest guaranteed? Yes — the rate is locked in at the time of booking and doesn't change for the tenure, regardless of what interest rates do in the market. This is one of the main reasons people choose FDs over market-linked instruments.

Can I book an FD for less than a year? Yes. Most banks offer tenures from 7 days upward. Very short tenures (under 6 months) typically earn lower rates. The calculator works for any tenure — just enter your exact duration.

What happens to my FD if I need the money early? You can break the FD before maturity, but the bank usually applies a penalty by reducing the applicable interest rate by 0.5%–1%. You still get your principal back; you just earn less interest than planned.

Is the FD calculator free to use? Yes — completely free, no login, no limits.

A fixed deposit is one of the least complicated financial products available, but the gap between "I'll earn about 7.5%" and "I'll actually receive ৳1,25,023 on my ৳1 lakh deposit in 3 years" is worth closing. The calculator closes it instantly.

Try the FD Calculator free at sadiqbd.com — know your exact maturity amount before you commit.