Generational Wealth Calculator

On the defaults, 100,000 with 10,000 added every year at a 7% return, across three generations of thirty years, reaches 106,982,152.26 after ninety years. A million of that was put in: the opening 100,000 plus ninety contributions of 10,000. The other 105,982,152 is compounding.

Where the number comes from

The two halves split more evenly than the headline suggests. The opening 100,000 compounds for the full ninety years and reaches 44,110,298, which is 41.2% of the total. The ninety contributions, each compounding only for the years remaining after it arrives, reach 62,871,854, or 58.8%. The steady saving does more of the work than the sum that started it, despite the starting sum having the longest run of any amount in the calculation.

Time dominates, and by how much

Dropping a single generation, from ninety years to sixty, takes the balance from 106,982,152 to 13,929,847. That is a fall of 87% from removing a third of the time. Halving the annual contribution costs 29%, taking it to 75,546,225; doubling it adds 59%, reaching 169,854,007. One percentage point off the return, 6% rather than 7%, roughly halves the answer to 50,357,203. So the horizon is the strongest lever by a wide margin, the return is second, and the contribution is third.

Ninety years of inflation is the missing number

Every figure here is nominal, which matters more over ninety years than over any horizon a person plans across alone. At 3% inflation across the same period, the 106,982,152 buys what 7,481,025 buys today. That is the number a plan measured in generations actually turns on, and the calculator does not produce it: it applies one nominal return and carries no inflation path. Consumer price inflation by country is published in the World Bank's open data.

Wealth does not transmit as cleanly as the arithmetic

The model assumes one balance passes intact from each generation to the next and is contributed to without interruption throughout. Measured reality is looser than that. Charles and Hurst estimated the age-adjusted elasticity of child wealth with respect to parental wealth at 0.37 before any bequest, with lifetime income and the ownership of particular assets together explaining nearly two-thirds of it. That describes how much similarity there is between generations rather than how much of one pot survives, but it points the same way: what passes down is far less than the whole.

What sits outside

Estate and inheritance taxes at each transition, which apply in many jurisdictions and at rates the model has no field for. The division of an estate between several heirs, which the calculation never does, since it keeps one balance compounding. Fees. The order in which returns arrive across ninety years. And the assumption that one family holds a single investment policy for the better part of a century without interruption.