The accuracy of your FIRE forecast depends heavily on the quality of your inputs. Our calculator offers both basic and advanced modes to give you as much control as you need. Here’s a guide to help you think through each field.
Core Financial Inputs
These are the fundamental building blocks of your financial plan.
Currency
Select your primary currency. All financial inputs should be in this currency, and all results will be displayed in it.
Monthly Income (After Taxes)
This is your "take-home pay." It's the amount of money you have left after federal, state, and local taxes, as well as other deductions like health insurance premiums, have been taken out of your paycheck. If using Advanced Mode with multiple people, enter this for each person.
- Include: Regular salary/wages, predictable freelance income, rental income, and any other consistent, reliable sources of cash.
- Exclude: Unpredictable one-time bonuses or gifts. These are better handled using the "One-Time Income" or "Lifestyle Events" features in Advanced Mode.
Monthly Expenses
This is the most critical number for your FIRE calculation. Be thorough and realistic. Your FIRE number is directly based on your annual expenses. If using Advanced Mode with multiple people, enter the expenses attributable to each person.
- Housing: Mortgage or rent payments, property taxes, HOA fees.
- Utilities: Electricity, water, gas, internet, phone bills.
- Transportation: Car payments, gas, insurance, maintenance, public transit passes.
- Food: Groceries and dining out.
- Insurance: Health, life, disability insurance premiums not deducted from your paycheck.
- Debt Payments: Minimum payments for student loans, credit cards, and other personal loans.
- Personal & Family: Childcare, clothing, subscriptions, gym memberships, hobbies, entertainment.
- Don't Forget: Irregular but predictable costs, averaged out monthly (e.g., annual vacations, holiday gifts).
Current Total Investments (Household)
This is the total value of your investment portfolio that you plan to use to fund your retirement. This should be the total for the entire household.
- Include: Money in 401(k)s, IRAs (Traditional and Roth), brokerage accounts, mutual funds, ETFs, and individual stocks.
- Exclude: The value of your primary residence, your emergency fund (typically 3-6 months of expenses in cash), or physical assets like cars. These are not income-producing assets for your retirement.
Expected Annual Growth Rates (%)
These fields project how your total household income and expenses will change over time, which has a significant impact on your timeline to FIRE.
- Income Growth: The average percentage you expect your total household income to increase each year (e.g., from raises, promotions). A typical rate might be 2-4%.
- Expense Growth: The average percentage you expect your total household expenses to increase each year. This is often tied to inflation. A typical rate might be 1.5-3%.
Expected Annual Investment Return (%)
This is the average annual growth rate you expect from your investments. It's an educated guess. Historical market returns are not indicative of future results. In Advanced Mode, this is split into two portfolios.
- Conservative: 4-5%. Might be appropriate for a portfolio heavy in bonds.
- Moderate: 6-8%. A common estimate for a balanced portfolio of stocks and bonds (e.g., 60/40). A 7% return is a widely used assumption.
- Aggressive: 9%+. Could be used for a portfolio that is 100% in stocks, but this also comes with higher volatility.
- Note on Inflation: For a more conservative projection, you can use a "real" rate of return, which is your expected return minus the inflation rate (e.g., 7% return - 3% inflation = 4% real return).
Safe Withdrawal Rate (%)
This determines your FIRE number when not using the FIRE Target Multiplier. It's the percentage of your nest egg you plan to withdraw each year in retirement.
- The 4% Rule: A widely cited rule of thumb, suggesting you can safely withdraw 4% of your initial portfolio value, adjusted for inflation, for 30 years with a low chance of running out of money. This corresponds to a FIRE Target Multiplier of 25 (since 100 / 4 = 25).
- Being More Conservative: For longer retirements (more than 30 years) or to add a larger safety margin, many people opt for a more conservative SWR of 3.5% or even 3%.
Advanced Mode Inputs
Advanced Mode unlocks powerful features for more detailed planning, including multi-person households, one-time events, portfolio splitting, and future lifestyle event simulation.
Household & One-Time Events
- Number of People: Set this to 1 for an individual or 2+ for a couple or family. The form will dynamically add fields for each person's income and expenses.
- One-Time Income/Expense: Use these fields for significant, one-off financial events that happen at the beginning of your plan, like an inheritance, a large bonus, or paying off a big debt.
- Additional Monthly Spending (Cash): Enter any regular monthly spending that you don't consider a core "expense" (e.g., hobbies, daily coffee). This amount is added to your total monthly expenses for all calculations.
Investment Strategy & Risk
- FIRE Target Multiplier: An alternative to the Safe Withdrawal Rate. This calculates your FIRE number by multiplying your annual expenses by this number (e.g., 25 is common). If set to a value greater than 0, it overrides the SWR for the FIRE number calculation.
- Savings Portfolio Split: This allows you to divide your future monthly savings into two different "portfolios," each with its own expected annual return rate. For example, you could allocate 80% of savings to an aggressive stock portfolio (Portfolio 1) and 20% to a more conservative bond portfolio (Portfolio 2).
- Investment Return Standard Deviation (%): This crucial input for the Monte Carlo simulation represents the expected volatility of your investments. A higher number means more dramatic swings (both up and down) in your portfolio's value from year to year. A typical value for a stock-heavy portfolio is between 10% and 15%.
Future Lifestyle Events
This is where you can model major life changes. Add events to simulate their financial impact on your FIRE journey. Both the main projection and the Monte Carlo simulation will take these events into account.
- Description & Year: Give your event a name (e.g., "Child's College Fund") and specify in how many years from now it will occur.
- Type & Amount:
- One-Time Expense: A single, large expense in a specific year (e.g., buying a new car for 25000).
- Recurring Expense (Annual): An ongoing expense that starts in a specific year and continues indefinitely, adjusted for inflation (e.g., childcare costs of 15000 per year).
- One-Time Income: A single income event in a specific year (e.g., selling a property for 100000).
- Income Change (%): A permanent percentage change to your total household income starting in a specific year (e.g., a planned career change resulting in a 20% salary increase, entered as 20).