Finance

Compound Interest Calculator

Project how a starting amount and optional monthly contributions grow over time under compound interest. Choose the compounding frequency — from daily to continuous — and see the year-by-year balance, total contributions, and interest earned.

Riepilogo dello strumento

Questo strumento accetta input strutturati e restituisce output deterministici nel browser, senza upload al server.

Nome dello strumento: Compound Interest Calculator
Intento dell'input: Fornisci il contenuto di origine da trasformare, validare o analizzare.
Intento dell'output: Ricevi un output normalizzato adatto a copia, riutilizzo o debug.
Esempio di input: $10,000 · 7% · 20 years · monthly · no contributions
Esempio di output: Future value ≈ $40,387 · Interest ≈ $30,387

Starting amount

CurrencyAnnual interest rate (%)YearsCompoundingMonthly contribution (optional)

Future value

$20,096.61

Contributions

$10,000.00

Interest earned

$10,096.61

Year	Contributions	Interest	Balance
Year 1	$10,000.00	$722.90	$10,722.90
Year 2	$10,000.00	$1,498.06	$11,498.06
Year 3	$10,000.00	$2,329.26	$12,329.26
Year 4	$10,000.00	$3,220.54	$13,220.54
Year 5	$10,000.00	$4,176.25	$14,176.25
Year 6	$10,000.00	$5,201.06	$15,201.06
Year 7	$10,000.00	$6,299.94	$16,299.94
Year 8	$10,000.00	$7,478.26	$17,478.26
Year 9	$10,000.00	$8,741.77	$18,741.77
Year 10	$10,000.00	$10,096.61	$20,096.61

Uses the compound interest formula A = P(1 + r/n)^(nt) — or A = Pe^(rt) for continuous compounding — with monthly contributions distributed across periods. Investment returns vary; this is a deterministic projection, not a guarantee.

Introduzione allo strumento

Panoramica dello strumento

Compound interest is interest that earns interest: each period, the balance is multiplied by 1 + r/n (or e^(r/n) in the continuous limit), so growth is exponential rather than linear. This calculator treats principal plus optional regular contributions the same way a savings account, fixed deposit, SIP, or index-fund projection would. Results are deterministic — real investment returns fluctuate — so treat the output as a planning estimate, not a guarantee.

Casi d'uso

Plan a retirement, emergency-fund, or down-payment target
Compare a lump-sum investment to a systematic monthly plan
Estimate future value of a fixed deposit or index fund
Quantify how compounding frequency changes the final balance

Esempi di input/output

Intento dell'input

$10,000 · 7% · 20 years · monthly · no contributions

Intento dell'output

Future value ≈ $40,387 · Interest ≈ $30,387

Intento dell'input

$0 · 8% · 30 years · monthly · $500/month

Intento dell'output

Future value ≈ $745,180 · Contributions $180,000 · Interest ≈ $565,180

FAQ

What is the compound interest formula?+

A = P · (1 + r/n)^(n·t), where P is principal, r is the annual rate, n is the number of compounding periods per year, and t is time in years. For continuous compounding the formula is A = P · e^(r·t).

How are monthly contributions handled?+

Contributions are converted to a per-period amount (for example, $500/month becomes $1,500/quarter when compounding is quarterly) and added at the end of each period before the next compounding step.

Is this a SIP (Systematic Investment Plan) calculator?+

Yes — use the monthly-contribution field and pick monthly compounding to model a typical SIP at an assumed annualized return.

Does compounding frequency matter much?+

At typical savings rates the difference between daily and continuous compounding is small, but over long horizons or higher rates it is noticeable. Try the same inputs across frequencies to see the gap.