Watch Compound Interest,
Accelerate Over Decades.
Free compound interest calculators: what lump sums and monthly savings grow into, when you reach a goal, and what every year of delay costs.
The Hockey Stick Inflection
Interest earned surpasses your annual cash contributions after year 10–12; exponential growth kicks in.
Monthly Recurring Contributions
Dollar-cost averaging smooths market volatility and compounds interest on new deposits continuously.
Rule of 72 Doubling Time
Divide 72 by your annual rate of return (e.g. 72 ÷ 8% = 9 years) to calculate capital doubling frequency.
CompoundPath Calculators
Lump Sum Growth Calculator
What a single deposit becomes at a given return — nominal and inflation-adjusted, with the doubling timeline.
Monthly Savings Growth Calculator
What regular monthly investing becomes — with a contribution-vs-growth breakdown and the year-by-year acceleration.
Savings Goal Timeline Calculator
When a target balance arrives given your deposits and return — or the monthly amount that hits it by a deadline.
Cost of Waiting Calculator
What each year of delay costs your final balance — the most expensive number nobody calculates.
Strategic Money Guides
Compound interest for people who have seen the chart and still did not feel it
The curve in three concrete sentences, and the two behaviors it actually asks of you.
Real returns: why your projection and your lifestyle will disagree
Inflation is the silent counterparty in every growth projection. Here is how to plan in dollars that still spend.
12 mistakes people make with compound interest
The recurring errors we see in compound interest — what causes each one, and the habit that prevents it.