United Kingdom: an age that moves inside your projection
The State Pension age is rising from 66 to 67 between 2026 and 2028, which is why this page opens at 67. The change is phased by month of birth rather than applied to a whole year's cohort at once, so if you were born in 1960 your own date sits somewhere inside that window and is worth entering. A further rise to 68 is already on the statute book for the 2040s and has been reviewed more than once, so anyone under about 45 should read 67 as the current rule rather than a fixed date.
The new State Pension replaces part of retirement income and is not modelled here. It is a flat rate built on National Insurance years rather than on what you earned, so it covers a much larger share of a modest income than a high one, which is the opposite of how an earnings-related pension behaves, and the reason a higher British salary needs a proportionally larger portfolio, not just a larger one.
British assumptions: a 7% nominal return and 2.5% inflation, a real return of 4.39% a year. The withdrawal rate opens at 3.5% rather than the American 4%, for the reason set out in the main guide.