Methodology and data sources
Last updated: September 12, 2026
This page explains how InvestmentCalc performs calculations, which external sources it uses and where the models' accuracy has limits.
Scenario calculations
Forward-looking results are mathematical scenarios. They use the amounts, time horizon, assumed return, inflation, fees and other parameters selected by the user. A constant expected return or inflation rate is a modelling assumption, not a market forecast.
Market prices and historical series
For supported stocks, ETFs and other market instruments, InvestmentCalc uses Twelve Data. CoinGecko is used for some current cryptocurrency prices. Availability, historical depth and update timing depend on the asset and the external provider.
Foreign-exchange rates
Current FX rates may use Coinbase Exchange Rates, while reference and historical fiat rates use Frankfurter. USDT/USD may be obtained from Coinbase. If a source is unavailable, some features may use a fallback implemented in the service or return an error.
Inflation
Historical inflation data comes from InvestmentCalc's local dataset based on the indicator Inflation, consumer prices (annual %): IMF International Financial Statistics via the World Bank, processed by Our World in Data. A historical inflation value is not a forecast of future inflation.
Fees, dividends and taxes
Where a calculator exposes fee or dividend settings, the result depends on the user's selections and that tool's logic. Personal tax treatment is not calculated unless the interface explicitly says otherwise.
Rounding and data delays
Displayed values may be rounded for readability. Market prices, FX rates, inflation data and calendar events can be delayed, revised by an external source or temporarily unavailable.
What the models cannot predict
InvestmentCalc cannot predict crises, rate changes, future volatility, taxes, currency behaviour, liquidity or actual future returns. Results are for scenario analysis and education, not a guarantee of an outcome.