By Rajendra Agrawal · Handwritten in Mandideep, M.P.

The RD maturity value
your bank didn't quite tell you

One evening at a bank counter started a years-long argument with a formula. This calculator is where that argument ended — enter your deposit details and see the number the way it should have been worked out from the start.

"No bank was giving the exact maturity value — I checked, by hand, more times than I can count."

Work out my maturity amount
2Formulas, one notebook
₹0Free to use
AnyWhole-month tenure
4Compounding types

The Calculator

What will your deposit actually be worth?

Both methods below come from the same notebook and answer the same question. Pick one, or try both — the numbers won't disagree by much, but the reasoning behind each is a little different.

The original formula from the paper — protected, and the one most visitors come here for.

Written up by Rajendra Agrawal, checked by hand before it was ever coded.

₹

Fill in the deposit details
and press calculate — this side fills in like a passbook entry.

Both calculations here are original, copyright-protected work by Rajendra Agrawal. If your bank's passbook shows a different figure, that gap is usually rounding policy on their end, not an error on yours.

Fixed Deposit Formula

What will one lump-sum deposit become?

Unlike an RD, an FD starts with one principal amount. Enter the amount, rate, tenure, and compounding frequency to calculate its maturity value.

Completed compounding periods stay whole; remaining months are handled separately.

₹

Enter the FD details
and press calculate to see the maturity value.

Two entries, one notebook

The Rameshta Formula and the Rajendranshul product

Both were written down while working through the same frustration, a few pages apart. Neither is "the upgrade" to the other — they're two honest ways of arriving at the same correct maturity value.

Rameshta Formula

Built specifically for recurring deposits, where a fresh installment lands every month rather than one lump sum. This is the formula named after the paper itself, and the one most people ask for by name.

Kept private: the calculator shows you the result and the reasoning behind it — not the working formula itself.

What goes in: monthly installment, the annual RD rate your bank or post office quotes, the tenure in months, and how often interest compounds.

Rajendranshul Recurring Deposit Product

A slightly later pass at the same problem, from the same notebook — same inputs, same care about not letting the compounding period turn into an awkward fraction.

Same protection: the working is kept private here too. What you get is the number, and how it breaks down.

Use it as a second opinion next to the Rameshta result — on most inputs they'll agree closely, because they're solving the same equation from two directions.

The story behind the work

It started with numbers that wouldn't match

A recurring deposit calculation should be simple arithmetic. It turned into years of checking, by hand, whether banks were getting their own numbers right.

What a recurring deposit actually is

A recurring deposit is a term deposit offered by banks across India, and by post offices too, for people who'd rather set aside a fixed amount every month than commit one lump sum. You earn interest at roughly the rate a fixed deposit would pay — it's really a fixed deposit built up one monthly installment at a time.

How it plays out over the tenure

Each month's installment sits for a different length of time before maturity, and interest usually compounds quarterly. Nothing is paid out until the deposit matures — the whole return arrives at once, at the end.

If you're saving toward something in the future but can only spare a little each month, an RD tends to suit that better than a fixed deposit. If you already have the lump sum sitting idle, a fixed deposit usually works out ahead. Tenures and thresholds vary by bank; this calculator simply asks for a whole number of months.

TDS applies once interest crosses the usual threshold — worth planning around rather than being surprised by at maturity.

Why it's worth doing at all

  • It turns saving into a habit rather than a decision you make new each month.
  • It builds toward a real amount without asking for much at once.
  • It leaves the rest of your money free — you're not locking everything away on day one.
  • It suits a first few years of saving as much as it suits a specific short-term goal.

this is the bit that actually annoyed me enough to write a paper about it —

Where the argument started

Before any of this was written down, Rajendra Agrawal was simply trying to open a recurring deposit. A bank executive pointed him toward the maturity figures published online. When he checked those figures against his own hand calculation, they didn't match — not by a rounding error, but by enough to notice.

He checked other banks next. Same story, repeated: bank-published maturity amounts sitting slightly below what the arithmetic actually gave. One or two banks landed slightly above instead. Nobody was landing exactly on the correct number.

The point of writing this down was never to catch anyone out — it was to hand both banks and depositors a formula that gets the maturity amount right, so the interest actually paid matches the interest actually earned.

Two things to sort out

Getting to a working formula meant answering two separate questions: how had the commonly used bank formula been derived in the first place, and where, precisely, did it go wrong.

First: trace the existing formula back to ordinary compound interest, so the error would be visible rather than assumed.

Second: fix the part that let the number of compounding periods become a fraction, and keep it a whole number instead.

Theory and reasoning

Why a fractional exponent is the whole problem

Compounding itself isn't in question here. Letting the number of compounding periods become a fraction is.

Starting from ordinary compound interest

Compound interest depends on the amount, the rate, the time, and how often it compounds. A fixed deposit compounds one amount, invested once. A recurring deposit compounds a new installment every month — each one invested for a different stretch of time, which is exactly why RD maturity needs its own careful handling rather than a fixed-deposit shortcut.

Where the common formula slips

The formula used across many banks lets the number of compounding periods drift into a fraction. Compound interest, as Rajendra Agrawal reasoned it through, should only ever apply over whole, completed periods — not a fractional cycle that never really happened.

Take five months of quarterly compounding: a fractional shortcut treats that as five-thirds of a quarter. The Rameshta Formula avoids that particular sleight of hand, while keeping the working itself private.

What stays private, and why

The internal steps of the Rameshta Formula aren't published on this page. What's here is the calculator — so you can see results, compare them, and understand what's wrong with the shortcut version, without the original method being handed out alongside it.

Two examples from the original paper

Example one: Apurva invests ₹10,000 a month for 24 months at 6.75% per annum, quarterly compounding — a tidy case, since 24 divides evenly into quarters.

Example two: Arpit invests ₹5,000 a month for 14 months at 6.25% per annum, quarterly compounding — the messier case, where 14 months doesn't land on a clean quarter boundary, which is exactly where shortcuts tend to come apart.

Where it landed

The conclusion, after all the checking: the same reasoning holds for monthly, half-yearly, and yearly compounding, not just quarterly — as long as the compounding period is always kept a whole number. The aim throughout was simply an exact maturity value, for banks and depositors alike.

Thanks

Rajendra Agrawal credited Anshul Agrawal, Satish Agrawal, Shravan Kumar Goyal, Shashank Goyal, Sagar Goyal, Rajesh Agrawal, Apurva Agarwal, and Renu Agrawal for sharpening the paper, along with others who supported the work along the way.

Why it matters

A small exponent,
a real difference

The formula many Indian banks use to work out RD maturity has one specific weak point: it lets the compounding exponent, n, land on a non-whole number. Compound interest doesn't really support that — periods either completed or they didn't.

Rajendra Agrawal traced that error back to its source and wrote the Rameshta Formula to keep n a whole number throughout, which is what produces the mathematically correct maturity value.

Fourteen months, seven months, or any tenure that refuses to divide evenly into your compounding period — this is built to handle that case properly, without publishing the method itself.

The core insight

Treat the number of compounding periods as a fraction, and the common bank-style approach can quietly produce an incorrect result. The Rameshta Formula exists to close that gap, while its working stays unpublished.

FeatureCommon bank formulaRameshta Formula
Whole-number exponent✗✓
Handles partial periods✗✓
Long or unusual tenures✗✓
Matches manual calculation✗✓
All compounding typesPartial✓

Built the slow way, on purpose

Every part of this calculator was checked by hand before it was ever trusted to run on its own.

⊕
The method stays private
You get the maturity result and the reasoning behind it — the internal working of the formula isn't published.
◎
Every compounding type
Quarterly, monthly, half-yearly, yearly — each handled with the same care, not a special case bolted on afterward.
⟁
Any whole-month tenure
Short, long, or an awkward number of months that doesn't divide neatly — this is exactly the case it was built for.
◈
One author's original work
Both formulas here are Rajendra Agrawal's own — copyright protected, and only available through this site.
⊗
No charge, no signup
Free to use, no account needed. Every depositor should be able to check their own number.
⊙
Principal and interest, side by side
See exactly how much of the maturity amount is what you put in, and how much it actually earned.

Questions people actually ask

About recurring deposits, and about the formula itself

A savings scheme where you deposit a fixed amount every month for a fixed tenure, and receive your total investment plus compound interest at the end. Minimum and maximum tenure rules vary by bank; this calculator accepts any whole number of months.
Rajendra Agrawal, after finding that bank-published RD maturity figures didn't match his own hand calculations. The calculator shows the result while the original method stays unpublished.
Both take the same inputs and solve the same problem — the correct maturity value for a recurring deposit. They come from the same notebook, a little apart in time, and you can switch between them above without re-entering anything.
A fixed deposit starts with one principal amount invested once; a recurring deposit adds a new installment every month. Because they behave differently, the formulas here are built specifically for RD, not adapted from an FD calculation.
Some bank-style calculations let the compounding period become a fraction when the tenure doesn't divide neatly into it, which nudges the result away from a manual calculation. Both formulas here were built specifically to avoid that.
Yes — TDS applies once interest earned crosses ₹10,000 in a financial year, typically deducted at 10%. Worth factoring into your plan rather than a surprise at maturity.
Interest is calculated and added every three months, which is how most Indian banks run their RDs. It nudges your effective return slightly above the stated annual rate, since you're earning interest on interest each quarter.
Yes — banks, post offices, cooperative societies, or NBFCs, as long as you know the rate and compounding frequency. Post office RDs typically compound quarterly at government-set rates.
Both formulas are original, copyrighted work by Rajendra Agrawal. Commercial use by a bank, fintech, or software company isn't permitted without a license — reach out if that's what you're after.
Calculation complete!