The latest articles on DEV Community by Coast FIRE Planner (@coastfireplanner). https://dev.to/coastfireplanner https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4227577%2Fe978af91-6274-40d5-8cb1-81cf36f821cc.png https://dev.to/coastfireplanner en Coast FIRE Planner Thu, 05 Nov 2026 04:07:08 +0000 https://dev.to/coastfireplanner/how-id-test-a-coast-fire-plan-against-1000-simulated-markets-302d https://dev.to/coastfireplanner/how-id-test-a-coast-fire-plan-against-1000-simulated-markets-302d <p>Coast FIRE is the point where your investments can grow to your retirement number with no more saving. Most calculators stop at a single date, which is the average case. If you stop saving exactly on that date, a plan like that only works about half the time.</p> <p>I built a free calculator that adds two things: your coast date to the month, and the share of 1,000 simulated markets where the plan reaches your goal (log-normal yearly returns, 15% volatility, fixed seed so results are reproducible). It also shows what-if rows for saving more, retiring later, lower returns or higher fees.</p> <p>It runs entirely in your browser, with no sign-up. You can try it at <a href="https://coastfireplanner.com/" rel="noopener noreferrer">Coast FIRE Planner</a>, and the formulas and sources are on the <a href="https://coastfireplanner.com/methodology" rel="noopener noreferrer">methodology page</a>.</p> <p>Feedback on the model is welcome.</p> personalfinance retirement math webdev