Interest & Savings Plan Calculator
Compute final balance, monthly contribution, lump sum or return rate — and compare up to 5 scenarios side-by-side in one chart.
Scenario 1
Inputs for "Scenario 1"
Click the icon to compute€
/month
historic global ETF ~6–8% gross
%
years
is being calculated
€
Result · Final balance
€195,573
after 25 years
Paid in
€80,000
Compound gains
€115,573
41% own contribution59% compounding effect
Wealth growth over time
Tip: add a new scenario to compare.
The active line is highlighted · Dashed = contributions only of the active scenario (no compounding effect).
How we calculate
This calculator uses the ordinary-annuity savings-plan formula with monthly compounding:
FV = PV · (1 + r)n + PMT · ((1 + r)n − 1) / r
- FV = final balance · PV = lump sum · PMT = monthly contribution
- r = monthly rate = annual rate ÷ 12
- n = number of months = years · 12
- Contributions are paid at the end of each month (ordinary annuity).
- For "monthly rate", "lump sum" and "return rate", the formula is solved for the unknown — the rate via numeric bisection.
Note: This is a model calculation without taxes, inflation, fees or market fluctuations. Real returns on ETFs etc. vary — but the compound-interest effect remains very reliable over long horizons. Not individual investment advice.
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