28/36 Rule Calculator
The 28/36 rule is the standard lender guideline for home affordability: housing costs should stay at or below 28% of your gross monthly income (front-end ratio), and all monthly debts combined should stay at or below 36% (back-end ratio). Enter your income and your PITI breakdown plus any other debts and the calculator shows both ratios, your maximum allowed payments, any remaining headroom, and a plain-English qualification verdict.
What is the 28/36 rule?
The 28/36 rule is a longstanding mortgage qualification guideline stating that a household should spend no more than 28% of its gross monthly income on housing costs (the front-end ratio) and no more than 36% on all monthly debt obligations combined (the back-end ratio, also called the debt-to-income or DTI ratio). Housing costs in this context means PITI: principal, interest, property taxes, and homeowners insurance. The back-end total adds car loans, student loans, minimum credit card payments, and any other recurring debt to that housing figure. The rule originated with conventional mortgage underwriting and remains the standard benchmark that most lenders use when evaluating whether a borrower can comfortably carry a home loan.
Front-end vs. back-end ratio: what each measures
The front-end ratio (sometimes called the housing ratio) focuses only on your monthly PITI: the mortgage principal and interest payment, monthly property tax, and homeowners insurance. It answers the question "what share of your income goes to keeping a roof over your head?" The back-end ratio expands that to every fixed monthly debt: PITI plus car loans, student loans, minimum credit card payments, personal loans, child support or alimony, and any other recurring obligation. It answers "what share of your income is already spoken for?" Lenders care about both because a borrower could pass the front-end test with modest PITI but still be overextended once car and student loan payments are included. Meeting both thresholds signals that you have enough income cushion to absorb unexpected costs without defaulting.
How the calculator works
Enter your gross monthly income (before taxes), your housing costs, and your other monthly debts. You can enter housing as a single PITI total or break it into its four components for a more precise figure. The calculator divides your housing by your income for the front-end ratio and divides the sum of all debts by income for the back-end ratio. It also works out the maximum housing payment and maximum total debt allowed under each threshold, and how much headroom you have before hitting the caps. The maximum-housing-given-your-other-debts figure is especially useful: it shows how much of the 36% back-end allowance is still available after your non-housing debts are accounted for, which is often the tighter constraint.
When the 28/36 rule does not tell the full story
The 28/36 rule is a useful starting point but it has real limitations. It uses gross income, not net income, so the percentages feel smaller than they are once taxes are withheld. It also ignores everyday costs: groceries, utilities, childcare, healthcare, transportation, and retirement savings. A household that passes the 28/36 rule could still be financially stretched if those expenses are large. Lenders themselves now routinely accept higher back-end ratios: conventional loans may allow up to 45% DTI with compensating factors such as strong credit or significant reserves, FHA loans can go to 43% (or 50% in exceptional cases), and VA loans focus on residual income rather than a fixed back-end limit. The 28/36 numbers are therefore a conservative baseline, not a legal ceiling, and borrowers who exceed them in one ratio are not automatically disqualified.
DTI ratio benchmarks by loan type
| Loan Type | Max Front-End DTI | Max Back-End DTI | Notes |
|---|---|---|---|
| Conventional (guideline) | 28% | 36% | Traditional 28/36 rule; best rates |
| Conventional (max) | 28-31% | 43-45% | Compensating factors may apply |
| FHA | 31% | 43% | Up to 50% with strong compensating factors |
| VA | No limit | 41% | Residual income requirement also applies |
| USDA | 29% | 41% | For eligible rural properties |
| Jumbo | Varies | 43% | Stricter credit/reserve requirements |
Lenders compare your debt-to-income ratios against these thresholds. Lower is always better. The 28/36 rule applies to conventional loans.
Frequently asked questions
What counts as housing costs in the 28/36 rule?
Housing costs means PITI: the monthly mortgage principal and interest payment, property taxes (annual taxes divided by 12), and homeowners insurance (annual premium divided by 12). HOA (homeowners association) fees are also typically included. It does not include utilities, repairs, or household expenses - those are part of your living costs but not counted by lenders in the PITI total.
What debts go into the back-end ratio?
The back-end ratio adds all recurring monthly debt obligations to your housing costs: car loans, student loans, minimum credit card payments, personal loans, child support or alimony payments, and any co-signed loans you are responsible for. It does not include utilities, groceries, subscriptions, cell phone bills, or other living expenses that do not show up on a credit report as a debt.
Can I still get a mortgage if I fail the 28/36 rule?
Yes, exceeding the guideline does not automatically disqualify you. Many lenders allow back-end DTI ratios up to 43-45% on conventional loans if you have compensating factors such as a high credit score, a large down payment, significant cash reserves, or stable long-term employment. FHA loans can go up to 43% (sometimes 50%), and VA loans have no strict front-end limit, relying on a residual income test instead. Exceeding the 28/36 thresholds does raise the lender risk profile, which can mean a higher interest rate or stricter underwriting.
How do I reduce my front-end ratio?
The front-end ratio drops when your housing cost falls or your income rises. Practical ways to lower it include increasing your down payment (which reduces the principal and therefore the interest payment), buying a less expensive property, shopping for a lower interest rate, or choosing a longer loan term (30 years instead of 15). You can also challenge an inflated property tax assessment or reduce insurance costs by comparing quotes. The calculator shows exactly how much monthly housing cost you can afford at your income level.
What is the difference between DTI and the 28/36 rule?
DTI (debt-to-income ratio) is the general term for any ratio of monthly debts to income. The 28/36 rule is a specific application of DTI: 28% is the front-end DTI limit for housing costs, and 36% is the back-end DTI limit for all debts. When a lender talks about your DTI, they are usually referring to the back-end figure - the 36% side of the rule.
Should I use gross or net income for the 28/36 rule?
Lenders use gross income (before taxes and deductions) when applying the 28/36 rule, so that is what this calculator uses. Keep in mind that gross income overstates what you actually take home, so the real share of your take-home pay going to housing is higher. A household in the 25% tax bracket that spends 28% of gross income on housing is actually spending about 37% of net income - a useful reality check when deciding what you can comfortably afford.