A model, not a calculator

Four paths.
Thirty years of decisions.
Sixty years of consequences.

Most rent-vs-buy advice compares two paths over ten years.

The decision deserves four paths over thirty, with retirement modeled through age 95 to verify funding.

TheHousingModel runs Rent & Invest, Buy Now, Rent, Then Buy, and Starter Home → Upgrade side by side against your actual financial life. It tells you when the verdict is "too close to call" instead of pretending otherwise.

Beta access on the model: password required. Don't have one? Get on the list. The calculator is free, no email.

4  strategies modeled in parallel 30-year  horizon · retirement through age 95 15  Quick-Start inputs · 7 core tabs + optional modules Excel-based.  Your numbers stay on your machine.
01 · The Premise

Two takes dominate the internet. Both are wrong.

The housing question gets reduced to a fight between two confident slogans, each pushed by people whose business depends on you believing them. The model exists because the real answer lives somewhere neither side will admit.

Take #1 — From the realtors
"Rent is throwing money away. Buy as soon as you can."
→ Ignores 30+ years of opportunity cost.
Take #2 — From the FIRE bloggers
"Renting and investing the difference always wins."
→ Assumes a discipline most households don't have.
The third position

Over a real 30-year horizon (with retirement modeled through age 95 and Age 85 NW as the wealth headline), the wealth-leader path is often not the recommended path. Some routes look attractive on net worth and quietly bankrupt you in the middle decades. The model exists to show you both at once: which path wins on wealth, and which one your household can actually survive.

02 · The Calculator Most Sites Give You

One number, one confident verdict, eleven things it can't see.

This is what the rest of the internet hands you: five inputs, a single answer, no second-guessing. Below is roughly what that screen looks like. Read the right column for everything it's pretending isn't there.

🧮 Generic Rent vs. Buy Calculator A typical online tool · static illustration
Verdict after 30 years
🏆 Buying wins by $1.08M
Buy path → $3.98M  (equity $3.73M + investments $254k)
Rent path → $2.90M
⚡ Free · No email required

Try the 4-Path Quick Verdict on your numbers.

Skip the single-answer trap. The free calculator ranks all four paths — Buy Now, Rent Then Buy, Starter→Upgrade, and Rent Forever — on the same household, so you can see which one actually wins.

Try the 4-Path Quick Verdict → ~60 seconds · 6 inputs · ranks all 4 paths

What this calculator can't see.

The simple version on the left gives you a number. It doesn't know about any of these. Each one moves the verdict.

  • Your actual take-home pay. No federal tax, no state tax, no city tax (NYC adds 3.876% on top). No 401k contributions or employer match. No HSA, no FSA.
  • Cash flow stress in the middle decades. Year 30 might look fine while Year 7 has you draining brokerage every month to make the mortgage.
  • Kids. No childcare ($25k+/yr per kid), no 529 contributions, no age-banded costs from daycare → after-school → self-sufficient.
  • The Rent → Buy path. Rent for N years, then buy. Often the actual winner. Never offered by these calculators.
  • The Starter Home → Upgrade path. Two transactions, capital-gains math on the sale, often house-poor in the middle years.
  • Sequence-of-returns risk. A bear market in your first 5 retirement years can erase a decade of gains. The simple calc assumes a flat 7%.
  • Property tax by town. A $1M house in town A vs. town B can differ by $15k/year, every year, for 30 years.
  • Existing cash, brokerage balances, student loans. Where you start changes what's possible.
  • Job loss, sabbaticals, parental leave. Real income isn't a flat line.
  • Refinancing windows. "What if rates drop to 4.5% in year 5?" Has a real answer.
  • The answer to "what if we just waited 1–3 years?" The simple calc can't tell you.
The simple verdict above says buying wins by ~$1M. The full 4-path model, which sees everything in the right column, runs the same household and recommends Rent, Then Buy instead — with Buy Now flagged 🟡 CAUTION.

The free 4-Path Quick Verdict calculator ranks the four paths on wealth. The full model adds the survivability check: cash stress, tax calibration, liquidity, FI timing, and downside scenarios. Try the free calculator →
03 · The Four Paths

Every scenario runs all four. Year by year, in parallel.

Most calculators force a binary. Real households compromise. These are the four strategies the model evaluates simultaneously, using one shared set of assumptions about your income, taxes, kids, and retirement.

PATH 01

Rent & Invest

Rent forever. Invest the down payment and the monthly differential into a diversified portfolio. The FIRE-blogger favorite.

PATH 02

Buy Now

Purchase a home in Year 0. Default: 20% down at the current mortgage rate. The realtor-approved default; the path your in-laws keep suggesting.

PATH 03

Rent, Then Buy

Rent for N years (default: 3) to build a larger cushion, then buy at the appreciated price. 20% down, no PMI. Often the actual winner.

PATH 04

Starter Home → Upgrade

Buy a modest starter at Y0. Sell and roll into a forever home a few years later. Two transactions, double the friction, often-overlooked tax mechanics.

04 · The Trajectory

Watch four paths diverge, then re-converge.

Illustrative projection for a dual-income household starting at age 30 with an $80k cushion, modeled at a $1.15M home price and 7.0% mortgage rate. The actual model takes 15 Quick-Start inputs, organized across 7 core planning tabs with optional modules for debt, cars, big lumpy spend, actuals, and stress-tests when you want them.

Age 30 Age 45 Age 60 Age 75 Age 90 $20M $15M $10M $0 Net Worth (today $) Rent → Buy Rent & Invest Buy Now Starter Home
Want to see how the verdict shifts on your numbers? The free 4-Path Quick Verdict calculator takes six inputs and ranks all four paths instantly. →
Illustrative only · Not financial advice
05 · The Verdict, Not A Chart

The output is a sentence you can act on.

Every run produces a Dashboard that reads like an honest planner, not a marketing calculator. The wealth-leader flag is separate from the six cash-stress diagnostics, because the highest-net-worth path is sometimes the one that bankrupts you on the way there. In the example below, the wealth leader is flagged 🟡 CAUTION. Only the #2 path is 🟢 GO.

Dashboard wealth checkpoints show Y30 and Age 85; retirement solvency is tested through age 95.

🏠 YOUR HOUSING DECISION — Side-by-Side Projection
Scenario: Home Price $1,150,000 · Mortgage Rate 7.00% · Rent→Buy years renting: 3 · Filing MFJ · NY · HENRY couple in NYC
⭐ Rent → Buy wins — $13,365,062 today-$ NW at Y30 · Leads next-best by $490,725 (3.7%)
⚖️ TOO CLOSE TO CALL: Rent → Buy leads Buy Now by just 3.7% at year 30. Run Sensitivity tab — returns/inflation assumptions will flip the order. ✅ No path fails the hard feasibility gates, but two paths are flagged 🟡 CAUTION and one is 🔴 DO NOT PROCEED. See House-Poor Check below.

Path Stress Check

Rent & InvestBuy NowRent → BuyStarter Home
Overall Verdict 🟢 GO 🟡 CAUTION 🟡 CAUTION 🔴 DO NOT PROCEED
Housing / Income ratio
(≥ 35% = stressed)
22.4% 47.0% 29.4% 31.6%
Stressed Years · Avg Severity
(years with ratio ≥ 35%)
🟢 0 yrs 7y · avg 43% · peak 47% 4y · avg 39% · peak 42% 24y · avg 41% · peak 53%
Post-Purchase Liquid Cushion
cash · brokerage · combined (mo)
4mo · 3mo · 7mo 6mo · 38mo · 44mo 6mo · 7mo · 13mo
House-Poor Check
(both stressed = 🔴)
🟢 Comfortable 🟡 Stretched (7y, 47%) 🟡 Stretched (4y, 42%) 🔴 Chronic (24y, 53%)

Wealth Leader — Year 30 Horizon

Highest year-30 NW (today $) ⚖️ TOO CLOSE TO CALL — Rent → Buy leads Buy Now by just 3.7% ($490,725 gap at Y30, today's $). Returns & inflation assumptions will flip the order.
Why it leads At this resolution, path choice matters less than execution. Focus on cash-stress diagnostics below. That's where the real differences show up.
When it took the lead Year 1 (age 35) — RENT, THEN BUY first took the #1 NW spot across all 4 paths. Lead held early ✅ — durable.

4-Path Wealth Scorecard

Rent & InvestBuy NowRent → BuyStarter Home
Year 5 NW$2.1M$2.2M$1.8M$2.2M
Year 10 NW$4.3M$4.7M$4.9M$4.3M
Year 20 NW$12.9M$14.1M$14.6M$13.5M
Year 30 NW (today $)$12.0M$12.9M$13.4M$12.5M
⭐ Age 85 NW (today $)$17.5M$18.0M$19.6M$18.6M
Year 30 Wealth Rank#4 (−10.0%)#2 (−3.7%)#1 leader#3 (−6.6%)
Age 85 Wealth Rank#4 (−10.6%)#3 (−8.1%)#1 leader#2 (−5.2%)
Look at what just happened: the only path flagged 🟢 GO — Rent & Invest — is in dead last on wealth. The wealth leader, Rent → Buy, is flagged 🟡 CAUTION. The path most likely to keep you financially sane (zero cash-stress flags, comfortable cushion) is the one that leaves the most money on the table. That gap between "safest" and "wealthiest" is the whole question. The model refuses to tell you which to pick — it just shows you both, honestly.

Liquidity-Adjusted View — Year 30

Rent & InvestBuy NowRent → BuyStarter Home
Y30 Home Equity (illiquid)$4.1M$3.9M$3.5M
Y30 Cash + Brokerage (truly liquid)$16.6M$15.4M$16.5M$14.4M
Financial Assets as % of Total NW96.0%85.9%84.3%85.4%

Two paths can show identical total NW with wildly different sleep-at-night metrics. A house worth $4M doesn't pay your utilities.

🔥 Financial Independence — When can you stop working?

Rent & InvestBuy NowRent → BuyStarter Home
FI Crossover Age
portfolio survives funding to age 95
Age 46 (Y13)Age 47 (Y14)Age 47 (Y14)Age 48 (Y15)
Stress-tested FI Age
same sim at 5% nominal return (FIRE-standard)
Age 49 (Y16)Age 51 (Y18)Age 51 (Y18)Age 52 (Y19)

The first year your portfolio could fund all path expenses without your salary. Bear-market stress-test included.

Full Cash-Stress Diagnostics — all 6 indicators

Rent & InvestBuy NowRent → BuyStarter Home
1️⃣ House-Poor Burden🟢🟡🟡🔴
2️⃣ Brokerage Drawdown Used🟢 0y🔴 7y🔴 13y🔴 12y
3️⃣ Brokerage Exhausted
Cash Shortfall at Y30
🟢 n/a🟡 $897k🟢 $0🟡 $322k
4️⃣ Emergency Fund (months)🟡 4.1🟡 3.0🟡 3.7🟡 3.7
5️⃣ Retirement Funded?🟢 to 95🟢 to 95🟢 to 95🟢 to 95
6️⃣ Chronic Housing Stress🟢 None🟡 7y · 47%🟡 4y · 42%🔴 24y · 53%
Stress Score (🔴 / 6)0113

Live output from build v173, sample data: HENRY couple in NYC. Your dashboard will tell a different story.

06 · Pressure-Test the Recommendation

It doesn't just answer "should I buy?" It tells you how confident to be in the answer.

Two purpose-built tabs do the pressure-testing. Sensitivity gives you a guide of stress tests across housing, market, career, and retirement assumptions — run them, save up to six snapshots side-by-side, and see which inputs actually move the verdict. MaxHomePrice exposes the affordable ceiling when the dashboard's yellow flag is hiding a darker number.

🎯 Sensitivity Bench — Same Household, Seven Scenarios
Illustrative pattern from running seven scenarios from the 14-scenario guide · save up to 6 snapshots side-by-side

Path verdicts across seven saved scenarios

LIVECheaper HouseHot Real EstateJob Loss Y3Infl + Rate ShockSequence CrashFrugal Retire
Rent & Invest🟢🟢🟢🟢🟢🟢🟢
Buy Now🟡🔴🔴🟡🔴🟡🟡
Rent → Buy🟡🟡🔴🟡🔴🟡🟡
Starter Home🔴🔴🔴🔴🔴🔴🔴
The pattern jumps out: Rent & Invest is 🟢 GO in every scenario. Starter Home is 🔴 DO NOT PROCEED in every scenario. The only real questions are whether Buy Now and Rent → Buy survive. Under aggressive real-estate or inflation shocks, they don't. The model isn't pretending; it's telling you exactly how robust the recommendation is.
🏠 MaxHomePrice — What You Can Actually Afford
A 🟡 CAUTION flag often hides a more honest number. This tab pulls it out.

Affordability at the current home price ($1,150,000)

PathCumDeficit @ Y30Affordable?Age 85 NW (today $)
Buy Now$896,833🟡 Stretched$18.0M
Rent → Buy$0✅ Comfortable$19.6M
Starter Home$322,261🟡 Stretched$18.6M
Rent & Invest✅ N/A (no purchase)$17.5M
Look carefully: Buy Now is flagged 🟡 Stretched here on a $897k deficit, and Starter Home shows $322k of strain — but Starter is the one flagged 🔴 DO NOT PROCEED on the Dashboard. Why? It's not just the cash math. Starter Home is running 24 years with housing costs above 35% of income (peak 53%). The cash math is half the verdict; the lived experience is the other half. Both have to land in the green before the model tells you to proceed.

Affordability Ladder — How long until you can buy without straining cash?

WaitBuy YearHome Price (then)DP + ClosingCash on HandCushion / Gap
0 yrsY1$1.2M$280k$153k❌ −$127k gap
1 yrY2$1.3M$297k$308k✅ +$11k
3 yrsY4$1.5M$334k$678k✅ +$344k
5 yrsY6$1.6M$368k$946k✅ +$578k

For the Rent → Buy path: at each waiting year, can the cash cushion cover the (appreciated) down payment + closing? This is how the model picks the optimal "rent for N years" value automatically.

07 · Inside The Model

What separates this from the calculator on your bank's website.

Real life is messy. The model is built to accommodate that mess, not to round it away so the chart looks cleaner.

15-input Quick Start, 7 core tabs, optional modules

A 15-input Quick-Start tab gets you to a first answer in 15 minutes. Seven core planning tabs underneath (Income & Taxes, Net Worth, Housing, Kids, Retirement, Spending, plus Start Here). Optional modules for ConsumerDebt, Cars, Big Events, Actuals tracking, and the Sensitivity / MaxHomePrice stress-tests when you need them. No more 32-section scroll-of-doom.

10-step Setup Wizard

A guided flow walks you through every must-edit tab in order: Start Here → Income & Taxes → Net Worth → Housing → Retirement → Kids → Spending → Cars → Big Events → Done. Skip ahead if you'd rather edit cells directly.

Personalization Checklist

A live dashboard at the bottom of Start Here tracks which sections you've customized vs. left as sample data. ⚠ next to any section that's still showing the HENRY couple's numbers, so you know what's still pretending to be yours.

Calibrate to your paystub

A one-time setup anchors the tax math to your actual take-home. Captures HSA, FSA, employer benefits, NYC's 3.876% city tax, and the withholding quirks generic brackets miss.

Couples or Solo

Toggle Household type to Couple or Solo. Solo households get single-income tax math, single emergency fund target, single retirement drawdown. Couples get full dual-income modeling with two paystubs, two 401k profiles, two SS streams.

Cross-State Move

The canonical NYC-rent → NJ-buy use case. Set a move year, post-move state, post-move city tax, and pick which paths apply the move. The model flips state + city tax math and (for buying paths) flips property tax to the destination town automatically.

6 cash-stress diagnostics

House-Poor Burden, Brokerage Drawdown Used, Brokerage Exhausted, Emergency Fund, Retirement Funded-through-95, Chronic Housing Stress. Wealth ranking is computed separately. A path can win on NW and still get flagged.

Stressed Years · Avg Severity

Doesn't just flag "house-poor in year 1." Reports how many years a path stays stressed, the average severity, and the peak. The difference between 5 stressed years and 24 stressed years isn't subtle.

🔥 FI Crossover Age

For each of the four paths, the year your portfolio could fund all path expenses without your salary. Comes with a stress-tested version at 5% return for the FIRE-conservative crowd.

MaxHomePrice ceiling

When a path gets flagged, a dedicated tab shows the affordable ceiling for each ownership path, plus a suggested "try these prices" ladder (−25% / −10% / current / +10% / +25%) so you can find your honest budget.

Sensitivity Bench

A guide of 14 named pressure tests grouped by category — 🏠 housing, 📈 market, 💼 career, 🏖️ retirement — each with specific inputs to change. Run them, save up to six snapshots side-by-side, and watch which inputs actually flip the verdict.

Brokerage drawdown + cash shortfall

When cash would go negative, the model pulls from brokerage. If brokerage is exhausted, the shortfall accumulates and compounds at the investment return rate, then gets subtracted from net worth. No silent overdrafts.

Liquidity-adjusted view

Splits net worth into illiquid home equity vs. truly liquid (cash + brokerage). Two paths can show identical NW with wildly different sleep-at-night metrics.

Kids and 529s

Up to 6 dependents. Childcare phases (daycare → after-school → self-sufficient), age-banded kid costs, 529 contributions starting at birth, college-cost waves.

Cars, plural

Up to 3 vehicle slots. Off / Buy New / Buy Used / Existing / Owned Outright / Lease, with per-path purchase timing. The Rent & Invest path might keep an older car longer than the Buy Now path.

Actuals tracking

Paste in your Rocket Money export (optional). The model auto-suggests budgets per category from your 3-month rolling spend, and tracks projection vs. reality month by month.

Refinance toggle

Optionally reset your mortgage rate mid-projection. Closing costs deduct from cash in the refi year. The "what if rates drop to 4.5%" what-if, modeled honestly.

Optional modules

RSU equity comp, startup ISO/NSO options, job loss / sabbatical / parental leave. Collapsed by default; expand only the ones that apply to you. No paying the complexity tax for features you don't use.

Model integrity audit

Built-in Watchdog, Fingerprint, and versioned Audit tabs flag broken cells, circular references, or version drift. The model tells you when something needs attention, not the other way around.

In-workbook FAQ + Feedback

A dedicated FAQ tab answers the recurring "wait, why does it do that?" questions inside the file itself. A Feedback tab captures notes from beta users so the model evolves with the people using it. The current build is shaped by people who've already run it on their own households.

08 · Is It For Me?

The honest qualifier, before you download.

This isn't a 30-second answer machine. It's a serious model. Five minutes below will tell you whether it'll actually help you, or just frustrate you.

This is for you if…

  • You're a couple or solo earner, roughly late 20s to early 40s, facing a first or trade-up home decision.
  • You're in a high-cost market and the "just buy" math no longer obviously works.
  • You have Excel 365 or Excel 2021+ on Windows or Mac (the model uses LET, XLOOKUP, and modern dynamic arrays).
  • You want a real model. Not a calculator that hides its assumptions and tells you what you want to hear.
  • You're willing to spend 15 minutes on the Start Here tab in exchange for a 30-year answer (and 30–60 minutes if you want to calibrate to your paystub).

Probably not for you if…

  • You want a one-screen "should I buy?" verdict in under a minute. (Try the calculator above; it's faster, but you've seen what it's missing.)
  • You're a real estate investor or landlord modeling rental income. (Wrong tool. This is single-residence household planning.)
  • You're looking for tax advice, legal advice, or a referral to a lender.
  • You're still on Excel 2019 or earlier. Modern dynamic-array formulas are required.
  • You want the answer to be "buy now." (The model is going to disagree with you, sometimes.)
09 · Objections, Pre-empted

The questions everyone asks before they download.

How do I know the math is right?
Every assumption sits in a labeled, editable cell. Mortgage amortization, capital gains, take-home pay, investment compounding, refinance closing costs, brokerage drawdown: all visible, all overridable. The model also ships with built-in Watchdog, Formula Audit, ShipReview, and Fingerprint tabs that flag broken cells, version drift, or stale formulas. No black boxes.
Why Excel? Why not a web app?
Three reasons. First: your financial details never leave your machine. Second: serious financial work (at hedge funds, in M&A, in corporate FP&A) still lives in Excel because it lets you see the whole model at once. Third: a web app would force you to trust a black box. The spreadsheet refuses to. (Requires Excel 365 or Excel 2021+; Google Sheets works for most features but a few emoji/conditional-formatting nuances may differ.)
What if I don't trust my own inputs?
Good. You shouldn't, alone. That's what the Sensitivity tab is for. It ships with a guide for 14 named pressure tests grouped by category (housing, market, career, retirement), each with specific inputs to change. Run each one, save up to six snapshots side-by-side, and watch which inputs actually move the verdict. If the top two paths stay tied across the whole range, the model says "too close to call" rather than pretending one wins.
How long does it take to set up?
First-pass with rough estimates: 15 minutes on the Start Here tab. 15 yellow cells, walked through by an optional 10-step Setup Wizard. A Personalization Checklist tracks which sections you've actually customized vs. left as sample data. Calibrated to your paystub: 30–60 minutes. Updating each quarter after: 5–10 minutes.
I'm single. Does this still work?
Yes. Toggle Household type to Solo on the Start Here tab. The model swaps in single-income tax math, a single emergency-fund target, single retirement drawdown, and a single SS stream. All four paths still run; the relative trade-offs just look different (rent dominates more often, buying needs a steeper down payment).
I want to model moving to a different state.
There's a dedicated Cross-State Move module. Set a move year, post-move state, post-move city tax rate, and which paths apply the move (the canonical case: Rent → Buy and Starter → Upgrade are NYC-rent → NJ-buy, while Rent & Invest and Buy Now stay in NYC). The model flips state + city tax math at the move year, and for buying paths it flips property tax + insurance to the destination town's rates automatically.
Does it tell me what to do?
It tells you what the math says. It will also tell you when the math is too close to call, which assumption flips the verdict, and which paths look attractive but trigger cash-stress gates in the middle years. A planner would do the same thing, in five hours, for $3,000.
Is there a free version?
Yes. The 4-Path Quick Verdict calculator is free, no email required: six inputs, the four paths ranked by projected net worth, and the wealth leader called out. What it deliberately leaves out is the survivability half of the verdict — the six cash-stress diagnostics, paystub-calibrated tax math, FI Crossover age, MaxHomePrice ceiling, and the Sensitivity Bench. That's the paid template. The calculator tells you who wins on wealth; the model tells you whether your household can survive it.
Beta Access

Stop guessing at a thirty-year decision.

The model is in private beta. If you've been sent a password, download below. If not, drop your email and I'll notify you at public launch — the first 100 beta-list signups get founding-member pricing.

🔑 Download the model

Password required. Sent separately by text or email.