Home Affordability Calculator: How Much House Can You Really Afford?
You already know that scrolling listings without a real budget is how you fall for a house you can't have.
And most advice just says "multiply your salary by 3x" and calls it done.
That doesn't work.
The number you actually need has a name: your home affordability — the price a lender will realistically let you borrow toward, based on your income, debts, and down payment. The calculator above gives it to you in seconds.
So here's what you'll walk away with: the exact math lenders use to set your budget (the 28/36 rule), the four levers that move your number, and how much income each price really takes. No hand-waving.
TL;DR — The Short Version
Key Takeaways
- Affordability comes down to your monthly payment, not just the sticker price.
- Lenders use the 28/36 rule: no more than 28% of gross income on housing, and no more than 36% on all debt combined.
- "Housing" means PITI: principal, interest, taxes, and insurance — plus PMI and HOA if they apply.
- Four levers move your number: income (up = more), monthly debt (down = more), interest rate (down = more), and down payment (up = more).
- A bigger down payment does double duty: it lowers your loan and can eliminate PMI once you hit 20%.
Get your number in the home affordability calculator above, then read on to understand it.
How Much House Can I Afford? (The Real Formula)
You can afford the home price whose total monthly payment fits within about 28% of your gross income for housing — and keeps all your debt under about 36%. That's the short answer, and it's how the calculator arrives at your number.
Here's the key mindset shift: lenders don't approve a price. They approve a monthly payment. Everything works backward from what you can comfortably pay each month.
The 28/36 Rule
The 28/36 rule is the gold standard lenders have leaned on for decades.
The 8-point gap is your room for everything else — car loans, student loans, credit card minimums. Carry more than that, and the back-end rule becomes the constraint.
The calculator applies both limits and uses whichever one caps you first. If you carry a lot of other debt, the 36% back-end rule usually decides your number. If you're debt-free, the 28% housing rule leads.
What "PITI" Actually Means
When lenders say "housing payment," they don't just mean principal and interest. They mean PITI:
📖 PITI
Principal — the loan balance you're paying down
Interest — the cost of borrowing
Taxes — property taxes, billed monthly into your payment
Insurance — homeowners insurance
Two more can stack on top: PMI (private mortgage insurance, if you put down less than 20%) and HOA dues.
Here's why this matters:
Two buyers with the same income can afford very different homes if one lives where property taxes are 0.4% and the other where they're 1.8%. Taxes and insurance can eat up close to a fifth of a typical monthly payment — so the calculator bakes them in, and you should too.
How to Use the Home Affordability Calculator (Step-by-Step)
You don't need to know any of the math — just feed it the inputs.
What to Enter
1. Gross annual income. Your total pre-tax income from all reliable sources. Buying with a co-borrower? Add both incomes.
2. Monthly debt payments. The minimum payments on car loans, student loans, credit cards, and personal loans. This is what drives your back-end ratio — leave it out and your number will be too optimistic.
3. Down payment. Enter a percentage or a dollar amount. Watch what happens when you cross 20% — PMI disappears and your affordable price jumps.
4. Interest rate and loan term. The calculator defaults to a current 30-year rate, but rates move — use a quote from your lender if you have one.
5. (Advanced) Taxes, insurance, PMI, and DTI limits. Open the advanced panel to match your local property-tax rate and insurance, or to model looser limits (say, an FHA-style 31/43) instead of the standard 28/36.
Pro tip: Your result shows which rule is capping you — front-end or back-end. That one line tells you whether to focus on the house (front) or on paying down debt (back).
A Worked Example
Let's run one. Meet Alex and Sam, buying together:
| Input | Value |
|---|---|
| Combined gross income | $95,000/year ($7,917/month) |
| Monthly debts | $550 (one car loan) |
| Down payment | 15% |
| Rate & term | 6.5%, 30 years |
Applying the 28/36 rule:
- Front-end cap (28%): $7,917 × 0.28 = $2,217/month for housing
- Back-end cap (36%): $7,917 × 0.36 − $550 = $2,300/month
The lower cap ($2,217) wins, so their housing budget is about $2,217/month. After backing out taxes (1.1%), insurance, and PMI, that supports a home price of roughly $311,000.
But here's the kicker:
Bump the down payment to 20% and PMI vanishes — the same monthly budget now buys about $346,000. That's the power of one lever. Try it yourself in the affordability calculator.
The 4 Levers That Change What You Can Afford
Your affordability number isn't fixed. Four inputs move it — and knowing which one to pull is the whole game.
1. Income (↑ raises your budget). More qualifying income lifts both the 28% and 36% ceilings. A raise, a documented side income, or adding a co-borrower all help. Lenders usually want a track record, so stable income counts most.
2. Monthly debt (↓ raises your budget). Every $100 of debt payment you erase gives back roughly $100 of housing room under the back-end rule. Paying off a small loan before you apply can meaningfully raise your price. See exactly where you stand with the debt-to-income ratio calculator.
3. Interest rate (↓ raises your budget). Rate changes the interest slice of every payment. Even a half-point drop can add thousands to what you can afford — which is why shopping lenders pays off. Model different rates in the mortgage calculator.
4. Down payment (↑ raises your budget — twice). A bigger down payment shrinks your loan and, once you hit 20%, removes PMI. Both effects push your affordable price up. It's often the fastest lever a saver can control.
Highest-impact move: for most buyers it's crossing the 20% down threshold — you cut the loan and drop PMI in one step.
How Much Income Do You Need? (Quick Reference)
Flipping the question around — "I want a $400k house; what do I need to earn?" — is just as useful.
| Home price | Rough income needed* | Est. monthly payment* |
|---|---|---|
| $250,000 | ~$70,000 | ~$1,600 |
| $350,000 | ~$96,000 | ~$2,250 |
| $450,000 | ~$123,000 | ~$2,875 |
| $600,000 | ~$165,000 | ~$3,850 |
*Estimates only; illustrative at ~6.5% rate, 30-year term, ~20% down (no PMI), low existing debt. Property taxes and insurance vary widely by location — run your own numbers above.
Afford vs. Comfortable: The Reality Check
Here's something most calculators won't tell you: the maximum a lender approves and the amount you'll comfortably live with are often two different numbers.
The 28/36 rule counts debt — but not your groceries, utilities, childcare, retirement savings, or travel. Max out your approval and those get squeezed.
Use the calculator's number as a ceiling, not a target. Many buyers aim a notch below — closer to 25% of income on housing — to keep breathing room. A house you can afford and still live your life in beats a house that owns you.
Ask yourself: at this payment, can I still save, handle a surprise repair, and not dread the first of the month? If yes, it's affordable in the way that actually counts.
Common Affordability Mistakes and Myths
- Myth: "Multiply your salary by 3–4x." A rough shortcut that ignores your debt, rate, and down payment. The 28/36 method is far more accurate.
- Mistake: Using take-home pay. Affordability runs on gross income. Using net pay understates your number.
- Mistake: Forgetting taxes and insurance. These can be a fifth of the payment. Leaving them out inflates what you think you can afford.
- Myth: "You must put 20% down." You don't — many loans allow far less. But under 20% usually means paying PMI.
- Mistake: Ignoring existing debt. Your car payment directly lowers your home budget through the back-end rule.
- Myth: "Pre-qualified means I can afford it." Pre-qualification is an estimate. What you can comfortably carry is your call, not the lender's max.
How Affordability Fits With Your Other Money Decisions
Your affordability number is the hub; several other decisions spoke off it:
Nail your affordability number, and every one of these decisions gets easier.
Bonus — The Fastest Way to Raise Your Number
Before you go, one move most buyers overlook.
If you don't like your affordability number, don't assume the only fix is years of saving for a bigger down payment. Look at your back-end DTI first.
Here's why:
Under the 36% rule, every dollar of monthly debt payment is a dollar taken out of your housing budget. So clearing a small debt frees that room right back up — often faster than saving thousands more for a down payment.
Say you're carrying a $200/month credit card minimum. Pay that balance off, and you don't "raise your income" — but you do lower your DTI enough to unlock roughly $200 more in monthly housing budget. At a 6.5% rate, that can add close to $30,000 to your affordable price.
Find out which balances are dragging your ratio with the debt-to-income ratio calculator, then re-run your budget above. It's the quickest lever most people can actually pull.
Next Steps
Here's your move: enter your numbers in the home affordability calculator above. Note your max price — and which rule is capping you.
If the back-end rule is your limit, a little debt payoff will stretch your budget; check your DTI and pick one balance to knock out. If the front-end rule leads, focus on your down payment and rate. Then aim a notch below the max for a payment you'll actually enjoy living with.
When you're ready to see real monthly numbers on a specific price, head to the mortgage calculator.
Frequently Asked Questions
Helpful Reading
- Mortgage Rates Guide — how your credit profile shapes the rate you're quoted
- Housing Inventory Trends — where buyers currently have leverage
- How Amortization Works — how payments split between principal and interest
About Jon Teera
Jon Teera is the Lead Developer and Founder of CalcLogix. Unlike traditional financial writers, Jon approaches personal finance as a data engineering problem. He built this calculator to solve for the full monthly cost — taxes, insurance, and PMI included — rather than the income multiplier most affordability tools stop at.
Read more about how we verify data →