To start, first, input the current age and select the biological gender, smoker or non-smoker, and the frequency of alcohol consumption. Regular drinking is defined as taking more than 2 drinks in a day for adult men and more than 1 drink for adult women.

Select your exercise habit. Suppose you consistently spend 3 to 5 hours weekly on vigorous exercise, 5 to 10 hours on moderate exercise, or 4 to 7 hours on a combination of vigorous and moderate exercise. The study shows that these physical activities may reduce mortality and improve longevity. Besides, age doesn't affect the benefit of the exercise you choose.

Input the blood pressure. Normal blood pressure is considered a healthy level if the "top number" (systolic) is lower than 120 mmHg and the "bottom number" (diastolic) is lower than 80 mmHg. If the systolic blood pressure is greater than 130 mmHg, or the criteria of Stage 1 hypertension or worse is met, the study shows an increased risk of all-cause mortality.

Check the life expectancy and probability of living longer. The table of longevity estimates can produce the following outputs:

1. Total life expectancy, namely the expected age at which a person may die.
2. Additional life expectancy. This is the average remaining years of a person's life at a given age.
3. Probability of living N more years. This can help answer the following questions: For example, if I am a 65-year-old retired man, should I prepare to keep financially strong for another 30 years, or is 20 years good enough? Is the probability of living that long high or not?
4. Probability of reaching a certain age. For example, what is the likelihood of becoming a centenarian (age 100+)?

Set the income expectation. The most important element of projecting future financials is the income. First, input current after-tax take-home pay in the "Monthly income" box. Then, set your income annual growth. The goal is to come up with a raise % that's appropriate for your skills, experience, role, location, and career aspiration. Next, input the age you want to retire in your mind now, and don't worry about the financial impact yet, which we will cover later. Also, select the tax filing status, which will be used for the calculation of tax on future investment income and retirement account withdrawal.

If you have multiple income streams, you can add extra items by clicking "List more income". For example, you can add a side job's income and specify the starting and ending age. If no start age is input, it means to start now. If no end age is input, it will occur as long as you're alive, such as social security benefits. 401k and IRA contributions are tax-deferred, so you need to input the gross contribution amount, and the tax will be calculated automatically. If you also save money in a Roth IRA, here $100, for example, this contribution should not be included in your cash income ($3,000 on the top) to avoid double counting.
Reminder: don't add investment income here because it will be considered by the yield input below.

Estimate your expenses and cash outflow. Input current average monthly spending and set an inflation assumption. 3% is normally good in the long term. If some cash outflows have a specific period or growth rate, such as a mortgage is paid only for 30 years and has no inflation. You can move that amount to the customized budget table by clicking "List more spending", filling in the starting and ending age at which this spending will incur in your life, and setting the specific growth rate.

Input the current savings amount and the asset allocation.
First, fill in your current savings balance by account type:

• Cash & trading, such as cash, checking account, savings account, and brokerage account.
• 401k & IRA, such as 401k plan, traditional IRA (individual retirement account), pension cash value.
• Roth IRA

Then, fill your current bond and equity allocation in approximate % of total savings. You can estimate this by reviewing the summary of bond & equity proportion provided in each of your investment and retirement accounts. The cash % is adjusted automatically.

Adjust future weights of asset allocation. This is one of the most important decisions for your investment portfolio; we call it strategic asset allocation. In the table above, for example, when you are 26 years old, you will invest more in equity (from 60% to 70%) and less in bonds (from 30% to 20%) to enhance the expected yield until age 45. When approaching retirement, at 45, you will increase bond weight and lower equity weight to reduce the market risk. After age 55, you will further reduce equity exposure and increase bond weight again to stabilize the investment income. This example is a normal pattern for a young worker's future asset allocation. Still, to make strategic asset allocation suitable, you should consider your budget (such as whether you have enough cash for an emergency fund), risk appetite, and investment horizon.

Set the annual investment yield expectation. This is another crucial assumption for your investment portfolio. For each asset class, an individual will prefer investing assets with higher or lower risk and, as a result, may have a higher or lower expected yield. However, we suggest avoiding using highly optimistic yields, such as 20% for equity. Even Warren Buffett's company share, Berkshire Hathaway Inc Class B (BRK-B), only generated an average annual yield of 11% for the past 28 years (from 5/1996 to 4/2024), according to Yahoo! Finance data.
Instead, we have the following recommended yield range:

• Cash: 2% ~ 4%
• Bond: 3% ~ 7%
• Stock: 6% ~ 12%

Check how much you can save in the future. The chart "Probability of Sufficient Savings" shows the outcome of your savings distribution of all ages. In this example, you have a high chance (80.5% probability) of saving more than $1 million at 50, the year set for retirement. In later years, you may see a red area showing the likelihood of deficiency, meaning running out of savings. The black area shows the probability of not being alive. If the red area is not significantly large compared to the other area, it can give you peace of mind in financials that you can probably retire comfortably.
Note: This statistical result is generated from Monte Carlo simulation. Even though your inputs are the same, you may see slightly different distributions each time you use this calculator due to the random seed's variation in time and browser.

Next, you can modify the age of retirement to see if you can retire a little earlier. For example, you want to retire three years earlier than planned and change the retirement age from 50 to 47 here.

Review the impact of early retirement. With early retirement, the financial outlook shows less savings than the prior forecast (smaller dark green area). If the deficiency probability (red area) is becoming significantly larger, you may want to reconsider whether this is the uncertainty you are willing to assume. Otherwise, you can also try out other plans, such as increasing income, reducing expenses, or modifying asset allocation, to have a decent outlook and keep your FIRE progress on track.