Methodology and assumptions

Market data and missing prices

Historical market prices and exchange rates are retrieved through Yahoo Finance. Depending on the selected series, macroeconomic data comes from FRED, the ECB or the Bundesbank. Availability and freshness depend on these sources.

Dates are aligned for display and comparison. The last available value may be carried forward on days without a quote; this does not create a trading day. Frozen examples disclose their own data date and assumptions.

Contributions and reinvestment

Initial capital is invested at the first available price. The contribution amount is invested at the selected frequency, so the same amount entered as monthly, annual or weekly contributions results in different total deposits.

For stocks and ETFs, separately supplied dividends are multiplied by the held quantity. After modelled tax, the net dividend is reinvested at the current price. Income of an accumulating fund may already be reflected in its price; an additional distribution is not invented.

Dividends and the annual allowance

The allowance and tax rate are model inputs. Gross dividends are accumulated per calendar year. Each payment is taxed only on the newly taxable amount above the allowance. Observed and projected dividends share the same allowance within a year, and a new calendar year starts a fresh allowance.

Example: €435 of gross dividends in one year, a €100 allowance and a selected tax rate of 25% produce modelled tax of (435 − 100) × 0.25 = €83.75. Previously taxed amounts are not taxed again.

Tax profiles are simplified presets. Personal loss offsets, partial exemptions, withholding taxes and capital gains taxes are not fully modelled.

History, Monte Carlo and regression

Historical mode uses available market prices. Monte Carlo extends the history with one random price path; drift and volatility are estimated from historical logarithmic returns using 252 steps per year. Rerunning can produce a different result. The chart is not a confidence interval obtained from many runs.

Regression extends a log-linear price trend fitted over up to five historical years. Projected dividends are estimated from up to the last 504 data points and modelled on scheduled quarterly dates when those dates fall on weekdays.

The positive outlook is a simplified indicator derived from drift and volatility, not an observed success rate. A trend or an individual random path cannot reliably predict future markets.

Interpreting the metrics

Ending value includes modelled contributions and reinvestment. Value growth and total return compare ending value with deposits; they are not a money-weighted annual savings-plan return.

The calculator CAGR uses the price ratio of the historical inputs and the simulation duration. Drawdown and volatility are derived from the modelled portfolio-value series and can be affected by contributions. Chart View calculates metrics for its selected price series separately.

Fees, inflation and limitations

Trading and custody fees and a personal inflation adjustment are not additionally deducted. Ongoing fund costs may already be reflected in prices. Series may differ in dividend coverage, price adjustments and available periods.

Results provide information and allow assumptions to be compared. Check the sources and inputs and distinguish historical observations from projections. This documentation explains the calculation and does not replace individual investment or tax advice.

Data sources

• Yahoo Finance
• FRED · Federal Reserve Bank of St. Louis
• European Central Bank
• Deutsche Bundesbank