MAKE THE NUMBERS MEAN SOMETHING
Compound interest calculator
Turn a long-term idea into a clear scenario. See your own contributions separately from projected growth, then change the assumptions to understand their impact.
Your assumptions
Range: 0–1,000,000,000
Range: 0–1,000,000,000
Range: -50–100
Range: 1–100
Results update as you change your assumptions.
Projected balance after tax
20 years at an assumed annual return of 7% · Month-end deposits
Chart shows balance before tax. The headline shows balance after tax.
An estimate based on your inputs. Actual outcomes can differ.
BEHIND THE CALCULATION
Understand your result.
Explore how your starting balance, monthly contributions and time could shape your investment growth.
How the calculation works
By default the annual return is effective, with monthly rate r = (1 + annual rate)^(1/12) − 1. Nominal mode with m compounding periods per year uses r = (1 + annual rate / m)^(m/12) − 1. For n month-end deposits, future value = P × (1 + r)^n + C × ((1 + r)^n − 1) / r. Month-start deposits multiply the contribution term by (1 + r). At 0%, future value = P + C × n. Inflation-adjusted value divides the balance after illustrative tax by (1 + inflation)^years.
Start with 10,000 and add 200 at each month-end for 10 years. At an assumed effective annual return of 6%, you contribute 34,000 in total and the projected balance is approximately 50,403. All amounts use your selected currency.
Assumptions & limitations
- By default contributions are made at month-end; you can select month-start. The starting balance is invested immediately.
- The return and inflation rate stay constant throughout the scenario.
- Returns are reinvested. Fees and withdrawals are excluded; an optional tax rate applies only to positive gains.
- Projections are illustrations. Real investments fluctuate and can lose value.