The Road to FIRE - Building the ISA Bridge Apex Calculator

I recently wrote about the ISA bridge and the idea of an “apex” - the point where an ISA has grown large enough to carry you from the day you stop work to the day a pension becomes accessible. That post worked through my own numbers: £147k in the ISA, £20k a year going in, a £36k/year target, and a handful of tables showing what the apex looks like at different ages and growth rates. Tables are fine for one scenario. They fall apart the moment someone wants to plug in their own numbers. So I’ve built a small calculator that does the same maths, for anyone’s figures. It uses client side calculations so no data leaves your browser/device. You can try it now at the ISA Bridge Calculator - sitting on my toolkit subdomain. You give it 4 things Your current age and ISA balance What you’re contributing each year What you’d want to withdraw each year during the bridge (in today’s money) The age the bridge needs to reach - 58 for private pension access, 68 for the State Pension, or another…