Platform calculators show gross compound interest and stop there. This one is honest about what erodes the headline number - defaults and idle cash, across three scenarios - and puts the result next to a stock ETF and a guaranteed bank deposit.
The calculator applies an annual drag to the advertised rate to reflect what real portfolios experience: 0.6 percentage points in the optimistic scenario (top-quartile platform, no defaults hitting your slice), 2.5 points in the base scenario (typical mix of defaults, partial recoveries and cash waiting to deploy), and 6.0 points in the pessimistic scenario (a bad platform year - elevated defaults, slow recoveries). These figures are calibrated to the gap between advertised and realised returns documented across the platforms in our market statistics.
"Reinvest" compounds interest monthly; "Withdraw monthly" pays interest out and keeps principal constant. The ETF line assumes a broad equity index fund at 7% nominal annual return - the long-run European average, with real volatility the chart cannot show. The deposit line uses 2.5%, a typical 2026 European term-deposit rate with state guarantees up to €100,000. The inflation toggle discounts everything at 2% per year. Nothing here is investment advice - it is arithmetic with honest inputs. Tax is not modelled: see our country tax guides.
Advertised vs realised returns, platform by platform - the data behind this calculator's drag assumptions.
The six risk types, the platforms that failed, and the checklist to run before your first deposit.
Five platforms with low minimums and clean records - plus a concrete starter allocation for €1,000.