The internet argues 4% versus 3.5%; both are answers to an American question. Your withdrawal rate depends on UK income tax on every pension pound you draw, a State Pension arriving in your late 60s, and your own horizon — so this page solves it: the Hundred Summers app's sustainable-spending solver finds the most you could draw with every year funded, and only then turns it into a percentage. Your figures never leave your browser.
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A withdrawal rate is a compression of a real question — “what can I spend?” — into a single number that forgets your tax position and your State Pension. This page runs the question properly: a year-by-year projection drawing what you need, grossing pension withdrawals up for income tax at real bands, crediting the State Pension when it arrives, and binary-searching the highest spending level at which every year funds. The percentage is derived from the answer, not assumed before it.
The result often surprises both camps. The 4%-is-doomed camp forgets the State Pension carries a big slice of every later year; the 4%-is-fine camp forgets tax and early retirement. And every steady-growth answer — including this one — carries the same caveat: sequence risk. The full Hundred Summers plan takes this same solver and stress-tests it through thousands of simulated markets and every historical window since 1928, which is the difference between an average and a promise. Related: drawdown calculator, how much do I need? and the 4% rule guide.
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