The 28/36 rule is a conservative guideline. FHA loans allow 31/43, and many conventional loans approve back-end ratios up to 45–50% with strong credit. Staying near 28/36 leaves room for savings.
How to use the 28/36 Rule Calculator
- Gross monthly income
- Mortgage principal and interest (or rent)
- Property tax (monthly)
- Home insurance (monthly)
- HOA and PMI (monthly)
- Other monthly debt payments
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your gross monthly income, your monthly housing costs (mortgage or rent, tax, insurance, HOA) and other monthly debt payments.
Tips
- Compare loans by APR and total cost, not just the monthly payment.
- Extra payments go straight to principal and can save a lot of interest.
- Pay off the highest-rate debt first if you want to save the most money.
- Check for prepayment penalties before paying a loan off early.
Common mistakes to avoid
- Stretching a loan term to lower the payment without seeing the extra interest.
- Paying only the minimum on credit cards.
- Forgetting fees that are rolled into the loan.
Inputs explained
| Field | What to enter |
|---|---|
| Gross monthly income | Amount in your currency |
| Mortgage principal and interest (or rent) | Amount in your currency |
| Property tax (monthly) | Amount in your currency |
| Home insurance (monthly) | Amount in your currency |
| HOA and PMI (monthly) | Amount in your currency |
| Other monthly debt payments | Amount in your currency |
What each result means
- Total housing costs = [Mortgage principal and interest (or rent)] + [Property tax (monthly)] + [Home insurance (monthly)] + [HOA and PMI (monthly)]
- Front-end ratio = [Total housing costs]÷[Gross monthly income]×100
- Back-end ratio = ([Total housing costs] + [Other monthly debt payments])÷[Gross monthly income]×100
- Maximum housing payment (28/36) = max(min(0.28×[Gross monthly income], 0.36×[Gross monthly income] – [Other monthly debt payments]), 0)
- Maximum total debt payments (36%) = 0.36×[Gross monthly income]
Example values
How the main result changes when Gross monthly income changes and everything else stays at the example values above:
| Gross monthly income | Back-end ratio (%) |
|---|---|
| 4,000 | 69.5 |
| 6,000 | 46.33 |
| 8,000 | 34.75 |
| 10,000 | 27.8 |
| 12,000 | 23.17 |
| 16,000 | 17.38 |
Formula
Front-end ratio = housing costs (PITI + HOA) ÷ gross monthly incomeBack-end ratio = (housing + other debts) ÷ gross monthly incomeMax housing = min(28% × income, 36% × income − other debts)Worked example
Inputs — Gross monthly income: $8,000; Mortgage principal and interest (or rent): $1,800; Property tax (monthly): $350; Home insurance (monthly): $130; HOA and PMI (monthly): $0; Other monthly debt payments: $500.
Results — Total housing costs = $2,280.00; Front-end ratio = 28.5 %; Back-end ratio = 34.75 %; Maximum housing payment (28/36) = $2,240.00; Maximum total debt payments (36%) = $2,880.00; Result = Above 28/36 but within 43% (may qualify).
Frequently asked questions
What is the 28/36 rule?
Spend no more than 28% of gross income on housing and 36% on all debts.
Does the 28/36 rule use gross or net income?
Gross (before-tax) income.
What counts as debt?
Minimum payments on cards, car loans, student loans, personal loans and child support.
What formula does the 28/36 Rule Calculator use?
Front-end ratio = housing costs (PITI + HOA) ÷ gross monthly income.