About FIRE Calculator Pro

Why does this site exist?

Because a single average return hides the risk that matters most. Many retirement calculators grow your savings at one steady rate and hand back one number. Real markets do not work that way: the returns in your first decade of retirement largely decide how much you can safely spend^[1]. And the classic 4% rule was built for 30-year retirements, while early retirees may need their money to last 50 or 60 years, where research points to 3.25%-3.5% as the safer range^[2].

We wanted calculators that answer the question people actually have, “will this work?”, honestly. That means showing how often a plan would have failed, not only when it succeeds on paper.

How are these calculators different?

• Risk testing on every calculator. Alongside the straight-line projection, each plan runs through a 2,000-run Monte Carlo simulation and a replay of every historical retirement in Damodaran's 1928-2025 data^[3]. You see a success rate, the range of outcomes and the worst start years.
• Social Security and pension handling. Income that starts later, like Social Security at 67^[4], lowers what your portfolio needs, but only from that age. Until then the portfolio pays your full spending. Every year's net need is valued at the rate implied by your withdrawal rate over your retirement, so with no other income you get exactly the 25x rule at 4%.
• Real dollars throughout. We convert your return with the Fisher equation, after fees and inflation, rather than simply subtracting. Every number is in today's money.
• Private. There is no account, no email capture and no ads. Your inputs are computed in your browser and are never sent to us or to our analytics. See the privacy policy for the details.
• Open about the math. Every formula, timing rule and limitation is documented on the methodology page.

Which calculators can I use?

Each calculator answers a different question, from your FIRE number to how long your savings will last.

How do we keep the content accurate?

Every outside figure links to its original source, and every worked example is computed by the calculator engine rather than typed by hand. These are our editorial standards.

• Sources. We cite primary sources first: the IRS, the Social Security Administration, the Bureau of Labor Statistics and the original research. All 136 sources, with what we use each for, are on the sources page.
• Updates. We recheck figures when they change at the source, such as new contribution limits, the yearly Social Security adjustment and each year's market data. Pages show the date they were last reviewed.
• Corrections. When we fix an error, we correct the page and log the change with its date: formula changes in the methodology changelog and data changes on the sources page. We do not quietly rewrite results.
• No invented facts. We do not publish testimonials, ratings or statistics we cannot source.

Who builds FIRE Calculator Pro?

FIRE Calculator Pro is written and maintained by Kashif Nazir Khan, a software engineer with a long-standing interest in early retirement and personal finance (LinkedIn). There are no ads on the site, and no company pays us to recommend its products.

How can I report an error?

Email iamkashifcs@gmail.com. Tell us the page and the figure that looks wrong, and where possible the source you are comparing it with. Confirmed fixes are logged with their date.

Is this financial advice?

No. The calculators are educational tools. They show what your assumptions imply, but they cannot know your full situation, your taxes or how markets will behave. For decisions about your own money, consider a fee-only fiduciary adviser, who is paid by you rather than by commissions and is obliged to act in your interest. Read our full terms and disclaimer.