Understanding what you can truly afford before approaching a lender saves you from overextending โ and prevents years of financial stress.
The 28/36 Rule (Standard Guideline)
The most widely used home affordability rule:
- 28%: Your monthly housing costs should not exceed 28% of gross monthly income
- 36%: Your total monthly debt payments (housing + all other debts) should not exceed 36% of gross monthly income
Max Housing Payment = Gross Monthly Income ร 0.28
Max Total Debt Payment = Gross Monthly Income ร 0.36
Example: $7,500 gross monthly income:
- Max housing payment = $7,500 ร 28% = $2,100/month
- Max total debt = $7,500 ร 36% = $2,700/month
- If car loan + student loans = $500/month, max housing = $2,200 (using 36% rule)
What "Housing Payment" Includes (PITI)
The $2,100/month must cover all housing costs, not just principal and interest:
| Component | Typical Amount |
|---|---|
| Principal | Varies |
| Interest | Varies |
| Taxes (property) | $200โ$600+/month |
| Insurance (homeowners) | $100โ$250/month |
| PMI (if <20% down) | 0.5โ1.5% of loan/year |
| HOA fees (if applicable) | $0โ$500+/month |
If property taxes + insurance + PMI = $700/month, your actual mortgage P&I budget is only $1,400.
Income Multiplier Method
A quicker rule of thumb: your home price should be 2.5โ3ร your gross annual income (conservative) or up to 4โ5ร in high-cost areas.
| Gross Annual Income | Conservative (3ร) | High-Cost Area (4ร) |
|---|---|---|
| $60,000 | $180,000 | $240,000 |
| $80,000 | $240,000 | $320,000 |
| $100,000 | $300,000 | $400,000 |
| $150,000 | $450,000 | $600,000 |
Back-Calculate Maximum Home Price
Given your maximum monthly P&I payment:
Max Loan = Payment ร ((1+r)^n โ 1) รท (r ร (1+r)^n)
Max Home Price = Max Loan รท (1 โ Down Payment %)
Example: $1,400/month P&I budget, 30-year mortgage, 7% APR, 20% down:
- r = 0.07 รท 12 = 0.005833
- Max loan = $1,400 ร (1.005833^360 โ 1) รท (0.005833 ร 1.005833^360) = $210,500
- Max home price = $210,500 รท 0.80 = $263,125
Down Payment Impact
A larger down payment doesn't just lower your monthly payment โ it eliminates PMI (usually required until you have 20% equity):
| Down Payment | PMI Required? | Monthly PMI (on $300k home) |
|---|---|---|
| 3% | Yes | ~$188/month |
| 5% | Yes | ~$150/month |
| 10% | Yes | ~$100/month |
| 20% | No | $0 |
PMI is typically 0.5โ1.5% of the loan amount per year.
Debt-to-Income Ratio (DTI)
Lenders calculate two DTI ratios:
Front-end DTI = Monthly Housing Costs รท Gross Monthly Income
Back-end DTI = Total Monthly Debt รท Gross Monthly Income
Conventional loan limits: Front-end โค28%, Back-end โค36% FHA loan limits: Front-end โค31%, Back-end โค43% VA loans: No front-end limit, Back-end โค41%
Example: $7,500 income, $1,800 PITI, $500 car/student loans:
- Front-end DTI = $1,800 รท $7,500 = 24% โ
- Back-end DTI = ($1,800 + $500) รท $7,500 = 30.7% โ (under both limits)
Hidden Costs First-Time Buyers Miss
Closing costs: 2โ5% of purchase price, paid upfront. On a $300,000 home: $6,000โ$15,000.
Moving costs: $1,000โ$5,000 depending on distance.
Immediate repairs/updates: Budget 1โ2% of purchase price in year one.
Ongoing maintenance: 1% of home value per year is the standard rule.
Utilities: Typically higher than renting โ larger space, you pay everything.
A $300,000 home budget should have an extra $20,000โ$30,000 in cash beyond the down payment to cover closing costs and first-year expenses.
The Pre-Approval vs Pre-Qualification Distinction
A pre-qualification is an estimate based on self-reported information. A pre-approval requires verified income, assets, and a credit check โ and is what sellers take seriously. Get pre-approved before viewing homes in your target price range.
Use our mortgage calculator to model exact monthly payments at different price points, down payments, and interest rates to find your true comfort zone.