Compound a lump sum — with optional recurring deposits — at yearly to daily frequencies, with effective yield, Rule of 72, and a growth chart.
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Compounding frequency
Compounding insights
How it works
A = P(1 + r/n)n·t — principal P grows at annual rate r compounded n times per year over t years. Higher compounding frequency lifts the effective yield above the nominal rate, which is why we show both.
The lump sum, the quoted annual rate, and how long it stays invested.
Yearly, half-yearly, quarterly (typical for FDs), monthly, or daily.
Maturity value, interest earned, effective annual yield, Rule-of-72 doubling time, and a chart.
The default scenario — quarterly compounding, the Indian fixed-deposit convention.
Input
₹1,00,000 · 8% p.a. · 10 years · quarterlyOutput
Maturity ≈ ₹2,20,804 · interest ≈ ₹1,20,804 · effective annual yield 8.243% · doubles in about 9 yearsCompound interest is interest that earns interest: with simple interest, ₹1 lakh at 8% earns a flat ₹8,000 every year, while compounded, each year's 8% applies to a bigger balance and the curve bends upward — slowly at first, dramatically over decades. This calculator shows exactly what that does to a deposit: enter a principal, rate, time, and compounding frequency, and read the maturity value, interest earned, and a year-by-year growth chart.
Frequency matters more than people expect, so it is a first-class control: yearly, half-yearly, quarterly (the Indian fixed-deposit convention), monthly, or daily. ₹1 lakh at 8% for 10 years is ₹2,15,892 compounded annually but ₹2,20,804 quarterly — same quoted rate, ₹5,000 apart — which is why the insights panel reports the effective annual yield alongside the nominal rate, exactly the pair regulators make banks publish. The Rule of 72 doubling estimate and the growth-as-a-multiple figure complete the intuition kit.
An optional recurring deposit adds a contribution every compounding period on top of the principal, covering RD-style saving alongside the pure lump sum. Nine currencies are supported, the scenario copies as text, and the standard disclaimer applies — the math is exact for your inputs, while real products add taxes, and inflation quietly erodes what the maturity amount buys. For monthly investing with step-ups and inflation views, the SIP Calculator is the purpose-built sibling.
Pick your currency and enter the principal — the lump sum being deposited or invested.
Enter the annual interest rate (the nominal, quoted rate) and the time period in years.
Choose the compounding frequency: yearly, half-yearly, quarterly, monthly, or daily — match the product (Indian FDs compound quarterly; savings accounts often daily or monthly).
Optionally set Add each period to contribute a recurring deposit every compounding period on top of the principal.
Read the maturity value, interest earned, and invested total in the sidebar, the effective annual yield and Rule of 72 doubling time in the insights, and the growth chart below. Copy exports the scenario as text.
Yearly through daily — with the effective annual yield showing exactly what the frequency adds to the nominal rate.
A contribution added every compounding period models RD-style saving on top of the lump sum.
Effective annual yield, Rule-of-72 doubling time, and growth as a multiple of what you put in.
Year-by-year growth plotted, and the invested-versus-interest split visualized.
Locale-formatted results, one-click text export, and instant defaults.
Project an FD with quarterly compounding at the bank's quoted rate.
See what monthly versus yearly compounding is really worth on the same deposit.
Watch the curve bend over 20–30 year horizons and locate the doubling points.
Model a starting balance with a recurring top-up each period.
The core is the compound-interest formula A = P(1 + r/n)^(n·t) — principal P at annual rate r, compounded n times per year for t years — computed period by period so recurring contributions can join each period as they arrive.
The effective annual yield converts the nominal rate plus frequency into the true one-year growth rate: (1 + r/n)ⁿ − 1. That is the honest comparison number between products quoting the same nominal rate at different frequencies. The Rule of 72 estimate — 72 ÷ rate ≈ years to double — is the classic mental shortcut, accurate within months for rates between roughly 4% and 15%, and the chart simply plots the balance at each year's end.
Sliders plus direct entry; rate in 0.05% steps, horizon up to 60 years.
Yearly (1), half-yearly (2), quarterly (4), monthly (12), or daily (365).
Optional recurring deposit per compounding period; the tool accepts principal-only, contributions-only, or both.
Nine currencies; text summary; defaults restore.
Inputs are out of range, or both principal and contribution are zero — at least one must be positive for there to be anything to compound.
Check the frequency first — quarterly versus yearly moves the figure — then TDS/taxes, which banks deduct along the way and this pre-tax model does not.
The rate field takes the nominal (quoted) rate; the effective annual yield in the insights is what that becomes after compounding. Comparing one product's nominal against another's effective misleads — compare like with like.
The model is pre-tax and pre-inflation: TDS, income tax on interest, and purchasing-power erosion all reduce what the maturity figure means in practice. Contributions are a fixed amount per compounding period (for monthly investing with annual step-ups, the SIP Calculator is built for it). Rates are assumed constant for the term — real floating-rate products reprice. The standard disclaimer applies: exact arithmetic on your inputs, informational rather than advisory.
All computation happens in your browser — amounts and scenarios are never uploaded or stored, and Copy writes only to your clipboard.
Match the compounding frequency to the actual product before comparing anything.
Compare products on effective annual yield, not nominal rate — frequency hides in the nominal.
Use the Rule-of-72 figure to sanity-check any projection at a glance.
Remember the output is pre-tax; deduct TDS/taxes for a realistic net figure.
Prefer adding regular contributions over waiting to invest a larger lump sum later.
Shop on the effective yield. Two deposits quoting "8%" can pay differently purely through frequency, and the effective-annual-yield readout is the number that makes them comparable. Small differences matter more than they look: over decades, half a percent of rate compounds into a visibly different curve — run both and see.
Protect the time axis. The chart's late-year steepening is the entire lesson of compounding: interrupting the term, or withdrawing interest instead of reinvesting it, flattens exactly the years that produce most of the growth. Choose terms you can genuinely leave untouched.
And run the number net: apply your tax rate to the interest and knock expected inflation off the rate for a real-terms view. The gross maturity figure is the headline; the net real figure is the decision-grade one.
Computation is period-by-period client-side: each of n·t periods grows the balance by r/n and adds any per-period contribution, which reduces to A = P(1+r/n)^(nt) when contributions are zero. Effective annual yield is (1+r/n)ⁿ−1; the Rule-of-72 readout is 72 ÷ rate. Yearly snapshots feed the growth chart. Validation requires non-negative inputs with at least one of principal or contribution positive. Currency formatting is locale-aware across nine currencies.
| Compounding | Maturity | Effective annual yield |
|---|---|---|
| Yearly | ₹2,15,892 | 8.000% |
| Quarterly | ₹2,20,804 | 8.243% |
| Monthly | ₹2,21,964 | 8.300% |
Frequency is a real but modest boost — rate and time dominate. The higher the rate and longer the term, the more frequency matters.
Savers projecting FDs and deposits, investors compounding lump sums over long horizons, students learning why frequency and time matter, and borrowers who want to see the same force working against them. Monthly investors with growing contributions belong in the SIP Calculator; fixed-EMI borrowers in the EMI Calculator.
Evidence and boundaries
Currency is a display choice unless stated otherwise. Lending, tax, disclosure, and investment rules vary by jurisdiction and provider.
Evidence standard reviewed .
Simple interest is always computed on the original principal — a flat amount per year. Compound interest recalculates on the growing balance, so each year earns more than the last; over 20 years at 8%, the compound outcome is more than double the simple one.
A real but modest amount at typical rates: on ₹1 lakh at 8% over 10 years, quarterly compounding beats yearly by about ₹5,000. It grows with rate and term — and it is why comparing products on effective annual yield, which the tool displays, beats comparing nominal rates.
A doubling-time shortcut: 72 ÷ rate ≈ years to double, so 8% doubles money in about 9 years and 12% in about 6. It is accurate within months for rates between roughly 4% and 15% — the insights panel computes it for your rate.
It deposits that amount every compounding period on top of the principal — quarterly compounding with ₹5,000 per period means four ₹5,000 deposits a year, each compounding from when it arrives. It models recurring-deposit-style saving alongside the lump sum.
The SIP Calculator is purpose-built for that — monthly contributions, annual step-ups, and an inflation-adjusted view. Use this one for lump sums and fixed per-period deposits at a chosen compounding frequency.
Before — interest income is typically taxable and banks may deduct TDS along the way, none of which the model includes. Apply your tax rate to the interest figure for a net estimate.