FIRE BoostCalculator

Calculate your FIRE goal

Estimate an invested target in today’s dollars. Apply it to your plan or keep your own amount.

$

Exclude child costs that you budget separately below.

Choose the age your retirement plan should cover.

3.5%

Lower rates increase the withdrawal-rate estimate.

Compare methods
Withdrawal-rate estimate
Adult annual expenses ÷ (SWR ÷ 100), plus child fund.
Benefit: Uses your withdrawal rate to estimate the adult investment target.
Limit: Does not test whether investments last through your planning age.
Total spending estimate
Adult annual expenses × years to fund, plus child fund.
Benefit: Shows total planned spending with no real investment growth.
Limit: Does not model investment returns during retirement.
Higher estimate
Larger adult estimate, plus child fund.
Benefit: Selects the larger target from both calculations.
Limit: A higher target does not establish greater accuracy or guarantee sufficient funds.

These methods use different assumptions. None calculates the probability that your investments will last through your planning age.

Children

Lifetime living costs Annual expenses × years
SWR-based target Annual expenses ÷ SWR
Temporary child fund Annual costs across support years
Estimated FIRE goal

Annual expense plan

Years start at FIRE. Amounts stay in today’s dollars.

Years after FIREChildren supportedExpenses / year
Assumptions and sources

Lifetime spending assumes no investment growth. The SWR target assumes invested withdrawals; its formula does not directly use years. The higher method uses the larger target. The temporary child fund covers annual costs only while support remains, up to 20 years per child. It assumes no real investment growth. It is added to the chosen adult target; it is not divided by SWR. The result is rounded up to a whole dollar. SWR applies only to the adult investment target. The temporary child fund is spent separately, so total withdrawals can initially exceed the selected SWR.

The 4% rule generally considers about 30 years. A selected rate does not prove your money will last your chosen period. This estimate does not simulate retirement withdrawals, taxes, benefits, or changing expenses. Withdrawal-rate background.

The annual child allowance uses the USDA middle-income benchmark of $233,610 in 2015 dollars. Adjusting with 2015 CPI-U of 237.017 and December 2025 CPI-U of 324.054 gives about $319,396 through age 17. Dividing by 18 years gives $17,744 per year, rounded to $18,000. This is a planning allowance at the December 2025 price level. Extending support to age 20 is your planning assumption. College, local cost differences, and sibling discounts are excluded. Adjust the annual cost for your family.

Send feedback

For FIRE Boost Calculator. Share a problem, idea, question, or kind word.

Up to 2,000 characters. Do not include passwords or private financial details.

Bug details (optional)

One PNG, JPEG, or WebP file. Maximum 2 MiB. Remove private details before uploading.

Your message, email, and screenshot go to the site owner’s Discord channel. Calculator inputs are not attached.

FIRE Boost Calculator

Runs locally. No account. Inputs stay in this browser.

Find the extra investment you need to reach financial independence.

Required FIRE boost
With selected boost
View results

FIRE boost needed at age 35

Investments at target age 40

Estimated FIRE age with selected boost

YOUR SCENARIO

Your investment outlook

Investment balance · in today’s dollars

AGE 30 — 40
Worst caseYour scenarioBest caseYour goal
Investment projections from age 30 to 40
Hover or tap the chart to explore
How the numbers work

All amounts are in today’s dollars. Annual investments are made in 12 equal monthly payments at month-end and maintain their purchasing power. The FIRE boost is extra money earned and invested at the selected birthday, after that month’s regular payment. It is also in today’s dollars.

Real return = (1 + market return) ÷ (1 + inflation) − 1. Each scenario uses its equivalent monthly rate for compound growth and the spreadsheet-compatible NPER function to estimate the time to your goal, separately before and after the FIRE boost. Fractional months are estimates between payments.

The chart stops at your FIRE age; goal ages can extend beyond it, assuming annual investments and returns continue. “Not reached” means the goal cannot be reached under those fixed assumptions. These are illustrative constant-return scenarios, not forecasts or probability bounds; taxes and fees are excluded.

FIRE means financial independence, retire early. Enter your own investment goal or use the goal calculator beside the field. Its temporary child fund covers remaining support years, separately from adult living expenses.

The recommended market return is a 6% nominal annual planning assumption. It rounds Schwab’s 5.9% annualized U.S. large-cap stock expectation for 2026–2035. This is an editable assumption, not a universal industry standard. Inflation remains the arithmetic mean of U.S. CPI-U December-to-December changes for 2016–2025. The model adjusts nominal return for inflation once.

Sources: Schwab capital market expectations and BLS CPI, table 5. Verified October 24, 2026. Values are bundled locally; the calculator does not fetch market data.

Build your FIRE boost

Increasing annual targets

First year

Final year

Annual targets to earn your FIRE boost

Money to invest as your boost, after tax and living costs. Regular annual investments are separate.

How this earning plan works

The plan uses the FIRE boost amount you set. It does not use the calculated shortfall to your FIRE goal. It divides that target across the years from your starting age to your boost investment age.

Targets follow an exponential curve. Before whole-dollar rounding, the final year's target is five times the first year's target. For a one-year plan, the full target falls in that year. Rounding keeps the annual amounts nondecreasing and their total exact.

The money is set aside each year and invested together at your selected boost age. No growth is credited before that birthday. All amounts are in today’s dollars. These amounts are earning targets; actual income can differ.