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§ Tools / Series 03 · Personal finance

Fixed deposit calculator

A deterministic, stateless calculator that turns a single term deposit into its full output picture: maturity value, gross interest, after-tax maturity, effective annual yield, and side-by-side comparison of how different compounding frequencies change the same deposit. Product-neutral: works as a Fixed Deposit, Term Deposit, or Certificate of Deposit — no country-specific tax law is hardcoded.

§ Transparency layer

Every output has a formula-trace line. Every input is audited as used / defaulted / unused. Nominal vs effective rate is a first-class toggle, not buried. Cumulative vs payout are explicitly separate modes — you cannot accidentally compare apples-to-oranges.

3
Presets
5
Compounding frequencies
2
Interest modes
5×
Rate scenarios
v1
Methodology
§ Start with a preset
Three product-neutral presets · adjust any field after.
Inputs
Everything you change reruns the math instantly. No save, no login.
01Deposit
02Rate
03Interest mode
04AdvancedRate Nominal APR · tax 0% · withholding 0%
Maturity value · gross
$11,607.55
Single deposit of $10,000.00 grows over 3 years at 5% quarterly compounding.
Gross interest$1,607.55
Effective annual yield5.095%
Principal
$10,000
10,000 × ones
Periodic rate
1.2500%
per quarterly · 4×/yr
Compounding periods
12
3 years × 4
Total cash received
$11,608
paid at maturity
§ Compounding comparison

How much does compounding frequency actually move the maturity number?

Same principal · same nominal rate · same tenure. The spread between yearly and daily is what you'd give up by choosing the wrong frequency.
CompoundingPeriods / yrPeriodic rateEffective annualMaturityInterestvs yearly
Yearly 15.0000%5.000%$11,576.25$1,576.25—
Half-yearly 22.5000%5.062%$11,596.93$1,596.93+$20.68
Quarterly selected41.2500%5.095%$11,607.55$1,607.55+$31.30
Monthly 120.4167%5.116%$11,614.72$1,614.72+$38.47
Daily 3650.0137%5.127%$11,618.22$1,618.22+$41.97
§ Rate scenarios

What if the bank's quote moves by 25 bps before you lock in?

-50 bps
4.50%
$11,437
interest $1,437
-25 bps
4.75%
$11,522
interest $1,522
Base
5.00%
$11,608
interest $1,608
+25 bps
5.25%
$11,694
interest $1,694
+50 bps
5.50%
$11,781
interest $1,781
§ Yearly schedule

How the balance compounds year-by-year

YearOpening balanceInterest creditedClosing balance
Y1$10,000.00+$509.45$10,509.45
Y2$10,509.45+$535.41$11,044.86
Y3$11,044.86+$562.68$11,607.55
§ Formula trace
every output, derived
  1. principal = 10000 × Ones = 10000.00 USD
  2. periodsPerYear = 4 (quarterly)
  3. periodicRate = 1.250000% (from 5% nominal apr)
  4. periods = round(3 × 4) = 12
  5. effectiveAnnualYield = (1 + periodicRate)^4 − 1 = 5.094534%
  6. maturityAmountGross = principal × (1 + periodicRate)^periods = 11607.55
  7. grossInterestEarned = maturity − principal = 1607.55
§ Input audit
no input silently ignored
amountused
annualRatePctused
compoundingused
currencyused
interestModeused
payoutFreqdefaulted
rateConventionused
taxRatePctdefaulted
tenureYearsused
unitused
withholdingRatePctdefaulted
§ Warnings
  • No tax or withholding modeled — FD/CD interest is generally taxable as ordinary income; the after-tax maturity will be lower than shown.
  • Early-withdrawal penalties and deposit-insurance caps are not modeled. Country-specific tax (TDS thresholds, slabs, exemptions) is whatever rate you type — no jurisdictional rules are hardcoded.
§ Golden references · locked in tests
Principal $1,000 · 12% · 10 years — the same deposit at four compounding frequencies. The spread is the whole reason the comparison table exists.
Yearly
$3,105.85
Quarterly
$3,262.04
Monthly
$3,300.39
Daily
$3,319.46
§ Same engine, headlessly

Rate normalization, compounding comparison, rate scenarios, yearly schedule, formula trace, and input audit are all reachable through public stateless REST. MCP candidates exist behind an unpassed launch gate and are not publicly available. Unknown inputs are rejected with a 422; ignored-in-context inputs are flagged in the audit — no input is silently consumed.

POST/api/v1/financial-calculators/fixed-deposit/calculate
POST/api/v1/financial-calculators/fixed-deposit/run
GET/api/v1/financial-calculators/fixed-deposit/schema
GET/api/v1/financial-calculators/fixed-deposit/defaults
MCP preview · not launchedcalculate_fixed_deposit_returns
methodology_version = financial-calculators.v1 · canonical = /en/tools/fixed-deposit-calculator
§ What v1 does not include
  • No workbook save/load — v1 is intentionally stateless.
  • No early-withdrawal penalty modeling.
  • No country-specific tax law (TDS thresholds, slab rules, exemptions) — tax is whatever rate you type.
  • No leap-year handling in daily compounding (uses 365 days flat; surfaced in warnings).
  • No premium prefill — there is no ticker data for FDs.
§ FAQ

Four things worth knowing

Q01Is this a Fixed Deposit, Term Deposit, or Certificate of Deposit calculator?+
It is all three. The math is identical — a single deposit, a fixed rate, a fixed compounding frequency, and a maturity date. The page is intentionally product-neutral: no country-specific tax law, TDS thresholds, deposit-insurance limits, or promotional-rate restrictions are hardcoded. Use it with the terminology of whichever market you are in.
Q02Why does the effective annual yield differ from the rate I typed?+
Banks usually quote the nominal APR (the rate compounded n times per year). A 12% nominal rate compounded daily produces an effective annual yield of about 12.747%. Toggle Rate convention → Effective annual to treat your input as the already-compounded yield instead. The Compounding comparison table makes the gap visible across yearly / half-yearly / quarterly / monthly / daily.
Q03Cumulative vs payout — what is the difference?+
Cumulative reinvests every period of interest until maturity (compound growth). Payout returns the principal at maturity and pays simple interest periodically (a CD-style income stream). The two are not interchangeable — payout deposits do not benefit from compounding, which is why cumulative deposits at the same nominal rate end up with a higher total cash received. We model the two as separate modes precisely so the gap is visible.
Q04How is tax computed?+
Tax and withholding are both applied to the gross interest earned. The tool does not model any country-specific tax law (no TDS thresholds, no slab logic, no exemptions) — it is whatever rate you type. After-tax maturity = principal + gross interest × (1 − tax rate). Withholding is reported separately so you can model a TDS-style withholding without conflating it with your final tax bill.

From calculation to research

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