An Engaging Data FIRE calculator alternative

What is Engaging Data?

Engaging Data describes itself as a virtual workshop and gallery where its author posts data visualizations, calculators, maps and other web projects^[1]. Its early retirement section collects four tools: a FIRE calculator that answers “when can I retire?”, a post-retirement calculator about whether your money will last, an interactive explainer of withdrawal rates and historical cycles, and a financial freedom calendar^[2].

The FIRE calculator is a pre-retirement tool. It asks for your age, savings and asset mix, income and spending, income growth, retirement spending, withdrawal rate and an average tax rate, and it can add extra income or expense streams between two ages. It then estimates the years until your savings reach the target, in one of three modes: a fixed real return, historical cycles that apply past returns in sequence, or a Monte Carlo simulation with returns you can set. A sensitivity view shows how the answer moves if you change spending or stock returns, and histograms show the spread of retirement dates^[3].

The post-retirement calculator starts at the other end. You enter savings at retirement, spending, retirement age and length, asset mix, tax rate, fees and extra income or expenses, and it shows, year by year, the share of historical cycles that had run out of money or stayed above set multiples of the starting balance, next to the chance of dying in each year from a choice of mortality tables^[4]. The FIRE calculator works in real, inflation-adjusted dollars and states that nothing you enter is sent to a server^[3].

How do Engaging Data and FIRE Calculator Pro compare?

How does each site approach the same question?

Engaging Data splits FIRE into two questions and gives each its own tool. That suits how many people think about it: first, how long until I have enough? Then, once I stop, will it last? The split lets each tool go deep. The FIRE calculator can model income growth and temporary income or costs while you save; the post-retirement tool can model spending cuts in bad markets and the odds of dying in each year^[3][4].

We run one plan through both phases. You enter your savings, contributions and spending, a retirement age and an age the money must last to, and every simulation runs the whole path: contributions while you work, withdrawals after you stop. A bad decade just before retirement therefore shows up in the result, not only a bad decade just after. The trade-off is depth in places: we do not model raises, spending cuts in bad years or mortality.

If you have already retired, the split matters less: you only need the second half. Engaging Data's post-retirement calculator is built for that, and so is our savings longevity calculator, which starts from the balance you have today and shows how many years it lasts at your spending, with the same Monte Carlo and historical tests as our FIRE calculators.

The other big difference is how the target is set. Engaging Data sizes the target as retirement spending divided by the withdrawal rate, with the tax rate on top^[3]. Ours starts the same way, but values each year's spending after Social Security or a pension. If a benefit will cover part of your spending from 67, the portfolio only has to cover the full amount until then.

What do our risk tests say about Engaging Data's example?

Engaging Data's FIRE calculator opens with a 32-year-old planning to spend $40,000 a year in retirement, with a 4% withdrawal rate and a 7% average tax rate. That gives a target of $1,070,000, which the default plan reaches at 53 in fixed-return mode^[3]. Entering $42,800 of spending (the $40,000 plus 7%) at a 4% withdrawal rate gives the same target in our engine, $1,070,000.

Suppose that household retires at 53 with exactly $1,070,000 and needs it to last to 95, a 42-year retirement. Here is how the plan fared in our two tests, and what Social Security changes.

Our calculation: 80% stocks and 20% bonds, 0.1% fees, US data 1928-2025^[5]. Historical: 57 start years with a full 42-year record. Monte Carlo: 2,000 runs, seed 2026.

With no other income, a 4% withdrawal over 42 years lasted in 86% of historical start years; the worst, 1966, ran out after 25 years. That fits the research: 4% was found safe for 30-year retirements^[6], and longer ones point to 3.25%-3.5%^[7]. Adding a $20,000 benefit from 67 means the portfolio only carries the full $42,800 for 14 years. Our target falls to $804,748. At exactly that amount the plan lasted in 75% of start years, because the heaviest withdrawals come first, so keep a margin above it. Kept at $1,070,000, it lasted in every start year.

Engaging Data can reach a similar answer with an extra income stream in its post-retirement tool^[4]. The difference is mainly where it happens: in our calculators the benefit lowers the target you save toward, so the FI age itself moves earlier. Get your own benefit estimate from the Social Security Administration^[8].

Does the choice of historical data matter?

It can. Shiller's series reaches back to 1871^[4], so it includes more start years and the economy of the late 19th century. Our 98 years run from 1928, covering the S&P 500 era, the Great Depression, the 1970s inflation and every market since^[5]. Neither is right or wrong. A longer series gives more cycles to test; a shorter one is closer to the markets you can invest in today. If two calculators give slightly different success rates for the same plan, the data window is often the reason.

We also never wrap the data around. A historical cohort only counts if every year of your retirement exists in the data, so long retirements have fewer cohorts. Our Monte Carlo draws whole years from the same history, keeping stocks, bonds and inflation from the same year together. Both choices are documented on our methodology page.

How do the Monte Carlo simulations differ?

Both sites use the term, but they draw the random returns differently. Engaging Data's FIRE calculator simulates thousands of paths to your target, drawing from the historical distribution of returns by default (8.1% real for stocks and 2.4% for bonds) or from averages you set yourself, so you can run optimistic or pessimistic cases^[3]. Results come back as percentile bands and a histogram of how many years it takes.

Our Monte Carlo is a bootstrap. Each simulated year is one real year from 1928-2025, picked at random, with that year's stock return, bond return and inflation kept together. We run 2,000 lifetimes from today to your plan-until age with a fixed seed, so the same inputs always give the same answer. If you expect lower returns than the last century delivered, the “Match my return” option shifts every year so the long-run average equals the return you entered, which plays a similar role to setting your own averages on Engaging Data.

How do you check an Engaging Data plan here?

Most of Engaging Data's inputs have a direct match in our FIRE calculator:

• Age, investments, income and spending. Enter them as they are. Engaging Data asks for income after tax, which matches our take-home pay.
• Asset mix. We test a mix of stocks and bonds only, so add any cash share to bonds.
• Retirement spending and tax rate. We do not apply a separate tax rate in the FIRE calculator, so enter retirement spending with your expected tax added, as in the example above.
• Income growth. We do not model raises. Enter today's savings, which gives a later and more cautious FI age if your pay will grow faster than your spending.
• Extra income streams. Social Security and a pension have their own fields. Temporary costs such as a mortgage or tuition are better handled on Engaging Data.

When should you use Engaging Data instead?

• You expect your income to grow. Its FIRE calculator has an income growth rate and temporary income and expense streams^[3].
• You want longevity in the picture. The post-retirement tool sets your odds of running out against your odds of dying, from SSA or Society of Actuaries tables^[4].
• You would cut spending in a downturn. Its spending flexibility setting models that directly^[4].
• You want the raw numbers. The post-retirement tool exports every historical cycle as CSV^[4].

When should you use FIRE Calculator Pro?

• You want one plan, start to finish. Saving and spending run through the same simulations, so one success rate covers both.
• Social Security or a pension is a big part of your plan. The benefit lowers your target from the age it starts, which moves your FI age.
• You are weighing Coast or Barista FIRE. Dedicated calculators find the balance where you can stop saving or go part-time.
• You live outside the US. Our FIRE and Coast FIRE calculators have UK, Canada and Australia editions with local accounts and government pensions.