Fixed Deposit Calculator

Field	Value	Copy
{{ row.label }}	$ {{ format(row.value) }} {{ row.value.toFixed(4) }} % {{ row.value }}

Year	Interest ($)	Ending ($)	Copy
{{ r.year }}	{{ format(r.interestCum) }}	{{ format(r.ending) }}

Month	Interest ($)	Ending ($)	Copy
{{ r.period }}	{{ format(r.interestCum) }}	{{ format(r.ending) }}

Fixed deposits are time locked savings that exchange a single upfront amount for a known payout after a chosen term. This fixed deposit maturity calculator explains how one lump sum grows with compounding and shows the total you receive at the end. You provide a deposit, select a rate and a term, and the result separates principal from interest for clarity.

The outcome is most useful when you want to compare choices across different terms and compounding plans. It also reports an effective annual yield so plans with monthly or quarterly crediting are easy to compare on one scale.

Enter the principal and the annual interest rate, then set years and months for the tenure. Choose how often interest is added to the balance so you can see the effect of annually, semi annually, quarterly, or monthly compounding on growth.

A quick example helps. A three year deposit at four percent with quarterly compounding turns ten thousand into a little over eleven thousand two hundred sixty eight, with the difference coming from interest that was credited each quarter and then tallied at maturity.

Treat results as estimates. Fees, penalties, and partial last periods are not modeled, and actual bank methods may differ.

Technical Details:

The calculator models a single lump sum that earns a nominal annual rate for a fixed number of months. It tracks periodic compounding, totals the interest that was actually credited, applies tax to interest, and then adjusts the maturity for inflation to express real purchasing power.

Nominal annual rate is handled as Annual Percentage Rate (APR). Results include Effective Annual Yield (EAY), which converts the specific term and compounding choice into a comparable one year rate after tax.

Interpretation is straightforward. The maturity amount is principal plus net interest after tax. Real maturity divides the maturity by the inflation factor for the same time span. EAY rises when compounding is more frequent or when tax and inflation are lower for the same term.

\begin{array}{l} n & = & ⌊ \frac{T_{m}}{perM} ⌋ \\ f & = & \frac{12}{perM} \\ r_{p} & = & \frac{r_{ann}}{100 \cdot f} \\ B_{n} & = & P \cdot {(1 + r_{p})}^{n} \\ I & = & B_{n} - P \\ I_{net} & = & I \cdot (1 - \frac{t}{100}) \\ M & = & P + I_{net} \\ M_{real} & = & \frac{M}{{(1 + \frac{i}{100})}^{\frac{T_{m}}{12}}} \\ EAY & = & {\frac{M}{P}}^{\frac{12}{T_{m}}} - 1 \cdot 100 % \end{array}

Symbols and units used in the calculation
Symbol	Meaning	Unit/Datatype	Source
P	Principal (initial deposit)	Currency	Input
r_ann	Nominal annual rate (APR)	Percent	Input
perM	Months per compounding	1, 3, 6, 12	Derived
T_m	Tenure length	Months	Derived
n	Completed compounding periods	Integer	Derived
t	Tax rate on interest	Percent	Input
i	Inflation rate	Percent	Input
M	Maturity amount after tax	Currency	Derived
EAY	Effective annual yield (net)	Percent	Derived
M_real	Inflation adjusted maturity	Currency	Derived

Worked example. Let P = 10,000, r_ann = 4%, tenure = 36 months, quarterly compounding (perM = 3), tax t = 0%, inflation i = 0%.

\begin{array}{l} n & = & \frac{36}{3} = 12 \\ r_{p} & = & \frac{0.04}{4} = 0.01 \\ B_{n} & = & 10000 \cdot {(1.01)}^{12} \approx 11268.25 \\ M & = & 11268.25 \\ EAY & = & {\frac{11268.25}{10000}}^{\frac{12}{36}} - 1 \approx 0.040604 (4.0604 %) \end{array}

The net maturity is 11,268.25 and the effective annual yield is about 4.0604%.

Validation & bounds extracted from code

Inputs, types, limits, and messages
Field	Type	Min	Max	Step/Pattern	Error Text	Notes
Principal	Number	0	—	—	—	Negative values forced to 0
Interest rate (APR)	Number	0	—	0.01	—	Percent per year
Tenure — years	Number	0	—	—	—	Floored to an integer
Tenure — months	Number	0	11	—	—	Clamped to 0 to 11
Compounding	Select	—	—	annually \| semiannually \| quarterly \| monthly	—	Maps to 12, 6, 3, 1 months
Tax rate	Number	0	—	0.01	—	Applied in 0 to 100 range
Inflation rate	Number	0	—	0.01	—	Annual average

Units, precision & rounding

Currency values are rounded to two decimals and shown with your locale’s separators.
Percentages in the summary table display to four decimals for comparability.
Interest is credited only at full compounding intervals; partial final months do not accrue.

I/O formats & encoding

Inputs and outputs
Input	Accepted Families	Output	Encoding/Precision	Rounding
Principal, rates, term	Numeric	Summary table	Money to 2 decimals; percent to 4	Standard rounding
—	—	Annual and monthly schedules	Money to 2 decimals	Per row via rounding
—	—	JSON snapshot	Inputs, derived metrics, schedules	As displayed
—	—	CSV exports	Metrics and schedules	As displayed

Networking & storage

Calculations run in your browser; no server request is made for inputs or results.
Copy and download actions create files locally or write to your clipboard.

Performance & complexity

Runtime scales linearly with the number of months in the term because each month is iterated to check whether a compounding event occurs.

Diagnostics & determinism

Given the same inputs, the engine returns identical results. Differences arise only from rounding and display locale.

Security considerations

No untrusted code execution; inputs are numeric and clamped to safe ranges.
Local downloads and clipboard writes avoid transmitting sensitive values.

Assumptions & limitations

Heads‑up Only completed compounding periods earn interest; partial months at the end earn none.
One deposit only; no recurring contributions or withdrawals.
Tax applies to total interest at maturity, not period by period.
Inflation is treated as a constant average over the term.
Fees, penalties, and tiered rates are out of scope.
Displayed currency format follows device locale; CSV may differ by app.
Very large numbers may exceed typical floating point precision.
EAY uses net maturity; comparing different tax rates mixes policy with return.

Edge cases & error sources

Zero term returns maturity equal to principal and EAY equals 0.
Tenure months outside 0 to 11 are clamped before calculation.
Negative inputs are coerced to zero.
Tax above 100 is treated as 100 when applied.
Inflation above 100 produces very small real values for long terms.
Rounding to two decimals per step can cause small drift versus exact math.
Locale differences in separators can change how numbers look when pasted.
Copy to clipboard may be blocked by system policy.
CSV import into spreadsheets may auto detect dates in the Period column.
Changing compounding late in setup can redraw charts after a short delay.

Scientific & standards backing

The method follows time value of money arithmetic for nominal rates, periodic compounding, and percent calculations. Effective annual yield is derived from the net growth ratio for the term.

Privacy & compliance

Calculations are client only and no data is transmitted or stored server side. Outputs are educational and not financial advice.

Step‑by‑Step Guide:

Compute fixed deposit maturity, effective yield, and real value with these steps.

Enter Principal as a nonnegative amount.
Set the Annual interest rate in percent.
Choose tenure using Years and Months.
Pick the Compounding frequency that matches your offer.
Optionally add Tax rate on interest and Inflation rate.
Review maturity, EAY, and schedules; switch tabs for tables and charts.

Example: Principal 10,000, rate 4, tenure 3 years, quarterly compounding, tax 0, inflation 0 → maturity ≈ 11,268.25 and EAY ≈ 4.0604%.

You now have the headline number, the yield, and the time path for easy comparisons.

FAQ:

Is my data stored?

No. Inputs are handled in your browser and files are created locally. Nothing is sent to a server.

Clipboard and downloads use your device’s capabilities.

How accurate is the maturity?

Amounts are rounded to two decimals and interest is credited only at completed intervals. Banks may add rules for partial periods, fees, or taxation.

What units and formats are supported?

All inputs are numeric. Currency displays follow your locale. CSV and JSON outputs reflect the same rounded values shown on screen.

Can I compare different compounding plans?

Yes. Use Effective Annual Yield to compare across monthly, quarterly, semi annual, and annual compounding on a like for like basis.

Does tax reduce the yield?

Yes. Tax applies to total interest and EAY is computed from the resulting net maturity, so higher tax lowers the comparable yield.

What does a borderline change in EAY mean?

A small difference, for example a few basis points, usually reflects compounding frequency or rounding and may not justify switching terms by itself.

Can I use it without a connection?

The calculation itself works in your browser. Charts may require one time access to fetch their assets depending on your setup.

Is there any cost or license requirement?

No payment is required to run the calculation. Use the results for personal or educational planning as appropriate.

Troubleshooting:

Nothing updates: ensure values are numbers and not empty text.
Charts do not appear: allow assets to load and try again.
Copy fails: grant clipboard permission or paste into a plain text app.
CSV opens strangely: import with comma as delimiter and set numbers as plain.
Very large values: reduce the term or rate to avoid overflow.
Unexpected EAY: confirm tenure months are correct and not zero.

If principal is zero, maturity equals zero and yield is zero by definition.

Advanced Tips:

Tip Match compounding to the quoted offer to avoid mixing APR and credited periods.
Tip Use EAY to compare different banks with the same risk tolerance.
Tip Add inflation to see real purchasing power over long horizons.
Tip Try both quarterly and monthly to see how frequency changes growth.
Tip Keep tax at your marginal rate on interest to avoid overstating returns.
Tip Save the JSON snapshot to reuse the exact same scenario later.

Glossary:

Fixed deposit: Single lump sum earning interest for a fixed term.
Principal (P): The initial amount you deposit.
APR: Annual Percentage Rate, the nominal yearly rate.
Compounding: Adding earned interest to balance at set intervals.
EAY: Effective Annual Yield, a one year equivalent net rate.
Real maturity: Maturity adjusted for inflation to reflect purchasing power.
Tenure: Total time the deposit remains locked.
Inflation rate: Average yearly rise in prices used for adjustment.