Coast FIRE Calculator Spreadsheet — Find Your Coast Number, 4% Rule Early Retirement Planner, Excel Download

Coast FIRE is the point where your invested money can carry you to retirement with zero further contributions. The Kollaz Coast FIRE Calculator finds that exact amount from 5 numbers (your age, what's invested now, expected real return, retirement age, and annual spend), and gives your coast number, progress percentage, and a plain-English verdict.

This is for someone who wants to know whether they can stop saving for retirement and let compounding carry them to their target.

Could you stop saving for retirement: today?

Coast FIRE is the milestone where your invested money is already enough: compound growth alone carries you to your retirement number, with zero further contributions. This calculator finds that exact amount. Type in 5 numbers (your age, what's invested now, your expected real return, your retirement age, and the annual spend you want in retirement), and get your coast number, how much you need invested today to coast, your progress %, and a plain-English verdict: "You're already coasting" or "You need $X more today."

With the sample data pre-loaded: a $50,000/yr retirement spend means a $1,250,000 coast number. At a 7% real return with 25 years to go, you'd only need $230,311 invested today to coast. Your numbers will be different. That's exactly the point.

WHAT THIS CALCULATOR DOES

- Finds your COAST NUMBER: your retirement target (annual spend x 25)
- Discounts it to TODAY: what compounding alone needs you to have invested right now
- Shows your PROGRESS % toward coast and the exact dollar GAP remaining
- Gives you a plain-English VERDICT you can act on
- Reveals your CROSSOVER AGE: when your money crosses the coast line on its own
- Projects 40 YEARS of compounding, year by year, with a coast-line chart

WHAT'S INSIDE (3 TABS)

1. Cover: branded welcome, 3-step quick start, the honest-math note
2. Inputs: 5 cream cells with built-in range checks (sample data pre-loaded)
3. Coast Dashboard: your numbers, verdict, 40-year projection table, chart

HONEST MATH, NOT HYPE

This tool uses the 4% rule of thumb: your target is about 25x your annual spend. That rule comes from Bengen's 1994 research and the Trinity Study, which found a 4% withdrawal worked about 95% of the time over 30-year periods. "About" and "~95%" are doing real work in that sentence: markets vary, and no rule is guaranteed. Every projection here is illustrative (a planning lens, not a promise). Your return assumption is yours to set (many planners use 5-7% real), so the model never goes stale.

EASY TO START: NO SPREADSHEET SKILLS NEEDED

Everything you touch is a cream-colored cell. Type over the sample numbers and the whole dashboard recalculates instantly.

COMPATIBILITY

Excel .xlsx, no macros. Tested working in Microsoft Excel (desktop + web) and Google Sheets. Nothing to install.

Try the live demo (view-only sample): https://docs.google.com/spreadsheets/d/173wt8bwVJlYk7rdK6PeIW8S6aiJbIubrRwIulu4r_PA/edit?usp=sharing

DETAILS

- Instant download: Excel .xlsx workbook, no macros, nothing to install
- Pairs with the Kollaz FIRE planners (the full planning suite), when you're ready to plan the whole journey, not just the coast

PLEASE NOTE

- This is an educational planning tool, not financial, tax, or legal advice
- Projections are illustrative and assume a constant real return; they ignore taxes, fees, inflation spikes, and sequence-of-returns risk
- Digital product: no physical item will be shipped

Built by the Kollaz studio. Smart financial tools for modern money. Created with AI assistance.

What is Coast FIRE?
The milestone where your invested money is already enough: compound growth alone carries you to your retirement number, with zero further contributions. No more saving required: growth does the work.

How do I calculate my coast number?
Type in 5 numbers (your age, what's invested now, your expected real return, your retirement age, and the annual spend you want in retirement). The calculator discounts your retirement target to today and gives you the exact amount you need invested right now.

Am I already coasting?
You get a plain-English verdict ("You're already coasting" or "You need $X more today"), plus your progress %, the exact dollar gap, and your crossover age (when your money crosses the coast line on its own).

Is the 4% rule behind this honest?
Yes: the tool uses the 4% rule of thumb (target approx 25x annual spend) with the caveats stated openly. Bengen 1994 and the Trinity Study found it worked about 95% of the time over 30-year periods, "about" and "~95%" doing real work. Every projection is illustrative (a planning lens, not a promise).

Q: Do I need spreadsheet skills?
A: No. Everything you touch is a cream-colored cell. Type over the sample numbers and the whole dashboard recalculates instantly.

Q: Can I try it first?
A: A showroom-only demo (branded Cover + one baked "Coast Snapshot (Preview)" tab, zero live formulas, diagonal PREVIEW watermark). Link goes in the description after upload.

Q: How does this relate to the FIRE Freedom Planner?
A: It's the coast-number specialist; the FIRE Freedom Planner (4580402761) covers the full five-lifestyle journey. They pair.

Q: Is this financial advice?
A: No: an educational planning tool. Projections are illustrative and assume a constant real return; they ignore taxes, fees, inflation spikes, and sequence-of-returns risk.

Format: Excel .xlsx workbook (no macros, nothing to install)
Tabs: 3: Cover (3-step quick start + honest-math note), Inputs (5 cream cells with built-in range checks, sample data pre-loaded), Coast Dashboard (numbers, verdict, 40-year projection table, coast-line chart)
Inputs: age, what's invested now, expected real return, retirement age, annual retirement spend
Features: coast number, discounted-to-today target, progress %, dollar gap, crossover age, 40-year year-by-year compounding projection with chart
Maker: Kollaz: Smart financial tools for modern money
Delivery: instant digital download