Budget Spreadsheet for the FIRE Movement
Build Your Monthly Savings Rate Tracker First
Start every fire budget spreadsheet with a simple formula that subtracts total spending from take-home pay then divides by income. Track January through December with columns for housing at $1,650, groceries at $420, and transport at $310 to hit a 62% rate on $6,800 monthly income. Update the sheet by the 3rd of each month so you see the exact percentage without estimates. Raise the rate from 45% to 55% by cutting one $180 streaming bundle and one $95 gym membership, then watch years-to-FI drop from 22 to 17. Log every coffee receipt under $7 and every utility bill so the numbers stay honest instead of optimistic. A 50% savings rate compounds faster than you expect when you automate the transfer to your brokerage on payday.
Log Investments With Dollar Amounts and Dates
Record every contribution by exact date and ticker so your fire budget spreadsheet shows real growth. Bought $4,200 of VTI on March 15 2023 at $198 per share and another $4,200 on September 10 at $214. The sheet calculates your cost basis and current value automatically. Add Roth IRA contributions capped at $6,500 for 2023 and note the exact deposit dates to avoid contribution room mistakes. Update prices monthly using closing values from the 1st. This level of detail turns vague progress into concrete milestones like crossing $250,000 net worth on a specific Tuesday.
Separate Spending Categories From Investment Buckets
Keep spending rows separate from investment rows so your fire budget spreadsheet never mixes the two. List rent, food, and insurance in one block totaling $3,150 then place brokerage transfers, 401(k) contributions, and HSA deposits in a different block totaling $3,650. The separation makes your 53% savings rate obvious at a glance. When you move $500 from a dining-out category into extra VTI shares you see the direct impact on your FI date. Revisit the categories every quarter and cut anything above your preset limits without exception.
Run the 25x Math With Live Numbers
Enter your current annual spending of $38,400 and multiply by 25 to get the $960,000 FI target inside the spreadsheet. Subtract your latest net worth of $187,000 to reveal the $773,000 gap that remains. Project forward using a 7% real return and watch the cell count down the remaining years. Adjust spending by $200 per month and see the target drop to 14 years instead of 16. The live calculation forces you to confront whether your current rate actually supports the date you want.
Review Tax Lots Without Guesswork
Use specific identification in your fire budget spreadsheet to track share lots by purchase date and price. IRS Notice 2014-21 and Form 8949 instructions allow HIFO sales when you maintain complete records. Record each lot’s acquisition cost and date so you can choose the highest-basis shares first during withdrawals. Consult a CPA before any sale to confirm your documentation meets Rev. Proc. 2019-09 standards. The sheet simply holds the data; your tax professional applies the rules.
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Frequently Asked Questions
Coast FIRE vs Lean FIRE vs Fat FIRE
Coast FIRE means you save aggressively until investments grow on their own to cover retirement at a normal age. Lean FIRE targets minimal annual spending around $25,000 so you need roughly $625,000 using the 25x rule. Fat FIRE requires $80,000 or more in yearly expenses and therefore a $2 million portfolio. A fire budget spreadsheet lets you model each scenario by changing one spending cell and instantly seeing the new FI date and required net worth.
Savings rate calculation
Divide total dollars saved and invested by total take-home pay each month. On $6,200 monthly income you save $3,410 when you contribute $2,100 to a 401(k), $800 to a brokerage, and $510 to an HSA. That produces a 55% savings rate. Update the fire budget spreadsheet every month with exact paycheck and transfer amounts so the percentage reflects reality rather than estimates.
Years-to-FI math
Multiply current annual spending by 25 to set your FI number then subtract present net worth. With $42,000 spending the target is $1,050,000. At a 7% real return and $2,800 monthly contributions you reach the goal in 15 years. Change the spending or contribution cells inside your fire budget spreadsheet and the remaining years update automatically.
Tracking net worth
Add every account balance on the same day each month: checking, brokerage, retirement plans, and subtract debts. Record $214,500 in assets minus $31,000 student loans for $183,500 net worth on the 1st. Chart the monthly change so you see the line cross $200,000 or $300,000 on an actual calendar date. Your fire budget spreadsheet stores these snapshots so progress stays visible and measurable.
Investment vs spending tracking
Keep two distinct sections in the sheet. Spending lists rent at $1,550, food at $480, and insurance at $210. Investment lists $1,200 401(k), $900 brokerage, and $400 HSA. The separation prevents accidental double-counting and makes your true savings rate clear. Export the totals to a summary tab so you review both categories side by side each month without mixing the data.
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