FIRE Calculator

Quick Answer

Last updated: 10 November 2026 ·How we calculate this: the 4% rule and monthly compounding

How This FIRE Calculator Works

FIRE stands for Financial Independence, Retire Early. Enter what you expect to spend each year, what you have invested, how much you invest each year and the return you expect after inflation. The calculator divides your spending by your withdrawal rate to get your FIRE number, then grows your savings month by month until they reach it. It also works out your Coast FIRE number: the amount that, left alone, would grow to your FIRE number by a normal retirement age.

How to Use the FIRE Calculator

1. Enter the yearly spending you expect once retired.
2. Enter your invested savings and how much you invest each year.
3. Enter a real return after inflation and a withdrawal rate.
4. Enter your age and a traditional retirement age for Coast FIRE.
5. Press Calculate to see your FIRE number and when you reach it.

FIRE Formulas

• FIRE number: yearly spending ÷ withdrawal rate
• At 4%: 25 × yearly spending; at 3.5%: about 28.6 ×; at 3%: about 33.3 ×
• Savings each month: balance × (1 + monthly return) + yearly investment ÷ 12
• Coast FIRE number: FIRE number ÷ (1 + real return)^(years until traditional retirement)

Key Terms

• FIRE: Financial Independence, Retire Early.
• FIRE number: the invested amount needed to cover your yearly spending.
• Safe withdrawal rate: the share of the starting portfolio you can take each year, raised with inflation.
• Real return: investment return after subtracting inflation.
• Coast FIRE: enough saved that it will grow to your FIRE number by a later age without new savings.

Worked Example

A 40-year-old spends $60,000 a year, has $250,000 invested, adds $50,000 a year and wants a cautious 3.5% withdrawal rate with a 5% real return.

• FIRE number = 60,000 ÷ 0.035 = $1,714,286
• Time to reach it: about 15 years 9 months, so financial independence near age 55.8
• Coast FIRE number for age 65: $506,233, so they have not reached Coast FIRE yet

Real-Life Examples

• Setting a target: $40,000 of yearly spending needs $1,000,000 at 4%.
• Timeline: $100,000 invested plus $30,000 a year at 5% real takes about 16 years 9 months.
• Coast FIRE: at 30, about $181,290 invested would grow to that target by 65 with no more saving.
• Testing a safer rate: $60,000 at 3.5% needs $1,714,286, reached in about 15 years 9 months in the example above.

FIRE vs Traditional Retirement Planning

• FIRE aims to stop needing a job decades early by saving 40% to 70% of income and investing it.
• Traditional planning works toward a set age, often 65 to 67, with Social Security and workplace plans filling part of the gap.
• Early retirees must also plan for health insurance before Medicare and for penalty-free access to retirement accounts.

The 4% Rule and Its Limits

The 4% rule comes from William Bengen’s 1994 study of US market history. He found that withdrawing 4% of a mixed stock and bond portfolio in the first year, then raising the amount with inflation each year, would have lasted at least 30 years in every period he tested. The 1998 Trinity study by three Trinity University professors looked at success rates for different stock and bond mixes and retirement lengths.

Early retirees may need their money to last 40 or 50 years, and future returns may be lower than in the past, so many people plan with 3% to 3.5%. Being flexible, such as spending less after a bad year, also makes the money last longer.

Types of FIRE

Common Mistakes to Avoid

• Using a nominal return. Use a return after inflation, since spending is in today’s dollars.
• Underestimating spending. Include health insurance, taxes, home repairs and travel.
• Treating 4% as guaranteed. It is a guide from past data over 30 years, not a promise.
• Ignoring sequence risk. A market crash early in retirement does the most damage.
• Counting your home as investable. Only count money that can produce income.

Frequently Asked Questions

References & Sources