(Documentatie in het Engels)

Compound Interest Calculator

What it does

Projects the growth of a starting balance under compound interest, with any compounding frequency (yearly to daily), scheduled contributions, and an optional inflation adjustment of the final figure. The projection runs as an exact monthly simulation whose monthly rate preserves the effective annual rate of the chosen frequency, so daily and monthly compounding compare correctly. Output is a yearly breakdown table, a growth curve, and summary totals (final balance, total contributed, total interest, inflation-adjusted final).

Everything is computed locally in your browser.

How to use

1. Enter the starting principal, annual rate, and number of years.
2. Pick a compounding frequency.
3. Optionally add a recurring contribution (monthly, quarterly or yearly) and an inflation rate.
4. Read the summary cards, hover the curve context, and copy the yearly breakdown as CSV.

The page URL encodes your inputs — use Copy share link to reopen or send the exact scenario.

Examples

10,000 at 5% for 10 years, monthly compounding, no contributions grows to 16,470.09 (6,470.09 interest).

Adding 100 per month to a zero starting balance at 5% for 10 years ends at 15,282.23 — 12,000 contributed, 3,528.23 interest.

With 2% inflation, the first example’s figure is worth 13,511.21 in today’s terms.

Good to know

• Contributions convert to a monthly equivalent (amount × frequency ÷ 12) regardless of the compounding frequency.
• The summary and table round to cents for display; the simulation keeps full precision internally.
• A non-whole year count, negative amounts, or an unsupported compounding frequency shows an error instead of a wrong number.