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Compound interest calculator

See how a starting balance and regular contributions could grow over time. Type any annual rate — there is no cap — or pick a real asset by ticker and project with its actual historical growth rate. Leave any field blank and it simply counts as zero.

A rough gauge for study. Projections are illustrative, not a forecast and not financial advice (NFA). A ticker's growth rate is what it did in the past — not what it will do next.

Initial deposit

Regular contribution

Growth rate

% p.a.

Any value, no cap. Negative works too. Blank counts as 0%.

Years

yrs

Compounding

› Advanced (optional)

Adjust for inflation

Off by default. Turn on to see values in today's dollars.

Illustrative projection · 20 years

$300,851

Projected balance · 7% p.a. (manual, compounded monthly)

Total contributions

$130,000

Total growth

$170,851

Contributions vs projected value

Projected value Contributions

Hover, drag (touch) or focus and use ← → to inspect a year.

Illustrative only, not advice. Assumes a steady rate every year with no fees or taxes. A rough gauge for study — not a forecast, a recommendation or financial advice (NFA).

How it works

Compounding

Growth is credited monthly or yearly on the balance held through each period. Contributions land at the end of each weekly, fortnightly, monthly or annual period (so weekly deposits fall four or five to a month). A manual rate is treated like a bank rate — split evenly across compounding periods.

Asset ticker (historical CAGR)

Daily adjusted closes from Yahoo Finance (dividends and splits included where Yahoo provides them; indices such as ^GSPC are price-only). CAGR = (last close ÷ first close in the window)^{1 ÷ years} − 1. The lookback can't reach past the first date with real data for that ticker. The CAGR is applied as an effective yearly rate, so monthly compounding doesn't inflate it. Rates are in the asset's own currency.

Inflation (optional)

Off by default. When on, each year's balance is divided by (1 + inflation)^years to show roughly what it buys in today's dollars. The default 2.5% p.a. is the middle of the Reserve Bank of Australia's 2–3% target and close to Australia's average annual CPI since inflation targeting began in 1993 (ABS). Override it with any figure.

balance_k = balance_k−1 × (1 + i) + deposits_k · i = rate ÷ n (manual) or (1 + CAGR)^1/n − 1 (ticker)

Illustrative, not advice

This calculator is a theoretical, educational estimate. It assumes a smooth, constant rate every year, which real investments never deliver — markets fall as well as rise, sometimes for years.
A ticker's CAGR is a historical figure for the window shown, not a forecast or an expected return. A different lookback can give a very different rate. Past performance is not a reliable indicator of future performance.
Fees, taxes, currency moves, inflation (unless switched on) and the timing of contributions are simplified or not modelled. Ticker data is delayed, third-party and may contain errors.
It does not tell anyone to buy, sell or hold anything and does not consider your objectives, financial situation or needs. General information only — not personal financial advice (NFA). Consider getting advice from a licensed professional before acting.

Educational content only · not financial advice (NFA) · @Dirindin533 / Adirindin Finance.