Mortgage To Debt Ratio Calculator
Your mortgage is only one line in your monthly budget, but for most homeowners it is the biggest one. This calculator shows what share of your total monthly debt payments goes to the mortgage, and if you add your gross monthly income it also checks your front-end and back-end debt-to-income ratios against the classic 28/36 lender benchmarks, with a verdict badge on every result.
The 28/36 benchmarks are the classic conventional underwriting guidelines. Your lender’s actual limits depend on the loan program, so treat the verdicts as orientation, not an approval.
Quick Answer
With a $1,800 monthly mortgage payment, $2,500 in total monthly debt payments and $7,500 of gross monthly income, the mortgage-to-debt ratio is 72.00%: nearly three quarters of every debt dollar goes to the mortgage. The front-end DTI is 24.00% (within the 28% guideline) and the back-end DTI is 33.33% (within the 36% guideline), so this borrower sits in the conventional comfort zone on both ratios.
Key takeaways
- Mortgage-to-debt ratio and DTI answer different questions: the first shows how much of your debt is housing, the second shows how much of your income goes to debt. Lenders underwrite on DTI, not on the mortgage share.
- A high mortgage-to-debt ratio is not automatically bad. 100% just means the mortgage is your only debt, which many lenders prefer over a lower share padded with car and card payments.
- The verdict that matters most is the back-end DTI: under 36% is the classic comfort zone, 36 to 43% is the caution band, and above 43% most lenders need compensating factors.
- Enter your full PITI payment (principal, interest, tax, insurance) rather than principal and interest alone, or the front-end DTI will flatter you.
- Quick Answer
- How to use the mortgage-to-debt ratio calculator
- The formula: three ratios from three numbers
- Worked example: $1,800 mortgage on $7,500 of income
- Mortgage-to-debt ratio vs DTI: which number does what
- DTI checkpoints lenders actually use
- What competing calculators miss
- How to lower your ratios in 5 steps
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the mortgage-to-debt ratio calculator
Three numbers in, three ratios out. Enter your monthly mortgage payment and your total monthly debt payments to get the mortgage-to-debt ratio; add your gross monthly income to unlock the front-end and back-end DTI ratios with 28/36 guideline verdicts. Results stay hidden until you click Calculate.
- Monthly mortgage payment: pre-filled with $1,800. Use the full PITI figure if you have it, since that is what lenders count as the housing payment.
- Total monthly debt payments: pre-filled with $2,500. Add the mortgage to every other recurring obligation: car loans, student loans, minimum credit card payments, child support.
- Gross monthly income (optional): pre-filled with $7,500. This is pre-tax income. Leave it and you get the mortgage-share ratio only.
- Read the badge: with income entered, a verdict badge appears under the results: green under 36% back-end DTI, amber from 36 to 43%, red above 43%.
The formula: three ratios from three numbers
All three ratios are simple divisions expressed as percentages. The mortgage-to-debt ratio divides one debt by all debts; the DTI ratios divide debts by income.
Front-end DTI = (monthly mortgage payment ÷ gross monthly income) × 100
Back-end DTI = (total monthly debt payments ÷ gross monthly income) × 100
The Consumer Financial Protection Bureau defines DTI as all monthly debt payments divided by gross monthly income, and its example works the same arithmetic: $2,000 of debts on $6,000 of income is 33%. Note what lenders exclude: utilities, groceries, insurance premiums and everyday spending are not debts, so they never enter the numerator.
Worked example: $1,800 mortgage on $7,500 of income
The calculator is pre-filled with this exact scenario, so you can press Calculate and watch every figure below reproduce to the second decimal. A borrower pays $1,800 a month for the mortgage, $700 a month on other debts ($2,500 total), and earns $7,500 gross a month.
Where the $2,500 of monthly debt goes
Against income, the same $2,500 is a 33.33% back-end DTI: $2,500 of every $7,500 earned is already spoken for before food, utilities or savings.
Mortgage-to-debt ratio vs DTI: which number does what
These two ratios sound alike and answer different questions. The mortgage-to-debt ratio describes the composition of your debts; DTI describes the weight of your debts against your income. Only DTI is an underwriting test.
| Mortgage-to-debt ratio | Debt-to-income ratio | |
|---|---|---|
| Question answered | How much of my debt is the mortgage? | How much of my income goes to debt? |
| Formula | mortgage ÷ total debt × 100 | total debt ÷ gross income × 100 |
| Lender use | Not a standard approval test | Core approval test on every mortgage |
| Worked example | 72.00% | front-end 24.00%, back-end 33.33% |
A 100% mortgage-to-debt ratio is not a red flag on its own: it can simply mean the mortgage is your only debt. What lenders actually penalize is a high back-end DTI, because that measures whether anything is left over. If you want the full DTI picture with borrowing headroom, the 45% DTI calculator works the same numbers from the lender’s side.
DTI checkpoints lenders actually use
The 28/36 figures are the classic conventional benchmarks this calculator verdicts against, but they are rules of thumb, not legal limits. The hard ceiling in US mortgage law is the 43% qualified-mortgage cap; individual loan programs set their own numbers on top of that.
| Checkpoint | Back-end DTI | Reading |
|---|---|---|
| Classic conventional benchmark | Under 36% | Healthy Comfortable for most lenders |
| Caution band | 36% to 43% | Caution Above guideline, inside the QM ceiling |
| Qualified-mortgage ceiling | Above 43% | Risky Most lenders need compensating factors |
The CFPB’s own debt-to-income worksheet tells homeowners to hold total DTI at 36% or less, and its qualified-mortgage guidance sets the 43% ceiling that defines the legal safe harbor for lenders. FHA, VA and USDA loans publish their own program caps, which differ from these conventional figures, so check the program guide or talk to a HUD-approved housing counselor before assuming the conventional benchmarks apply to your loan.
What competing calculators miss
Most DTI tools compute the same two ratios and stop. Checked against the top results for this keyword, five gaps stand out:
- 28/36 rule calculators (OnlyCalculators, Omni Calculator): solid on the two DTI ratios with headroom math, but neither computes the mortgage’s share of total debt, so you never learn whether housing or the other debts are the problem.
- Generic DTI calculators (finexplained, CalcRegistry): good gross-vs-net framing and program notes, but no verdict badge, no mortgage-share angle, and worked examples that do not run in the tool itself.
- Thin DTI pages (loancalczone and similar): a bare form with a one-line answer and no explanation of what counts as debt, which is where most DTI mistakes start.
- The CFPB’s own worksheet: authoritative and printable, but it is a static PDF: no interactivity, no verdicts, no what-if.
- The gap this page fills: the mortgage-to-debt ratio nobody else computes, both DTI ratios with 28/36 verdicts, a live verdict badge wired to your numbers, the worked example pre-filled so every figure in this article reproduces in the tool, and honest program checkpoints instead of a single pass/fail line.
How to lower your ratios in 5 steps
Lower ratios come from smaller debt payments or larger income. The fastest moves target the numerator first, because lenders count required payments, not balances.
Frequently asked questions
It is the share of your total monthly debt payments that goes to your mortgage: monthly mortgage payment divided by total monthly debt payments, times 100. A result of 72.00% means 72 cents of every debt dollar pays the mortgage.
The mortgage-to-debt ratio compares one debt to all your debts; DTI compares all your debts to your income. DTI is the ratio lenders underwrite against. This calculator reports both so you can see whether housing or your other debts are driving the total.
There is no lender standard for it. A higher share usually just means the mortgage dominates your debts, and 100% can simply mean the mortgage is your only debt. Judge the number alongside your back-end DTI: under 36% is the classic comfort zone.
Car loans, student loans, minimum credit card payments, personal loans, child support, alimony and any other fixed monthly obligation, plus the mortgage itself. The CFPB’s debt-to-income worksheet uses the same list. Utilities, groceries and insurance premiums are not debts and do not count.
As a benchmark, yes; as a hard limit, no. Conventional underwriting still treats 28% front-end and 36% back-end as the comfort zone, but the legal ceiling is the 43% qualified-mortgage cap, and automated underwriting can approve higher ratios when credit and reserves are strong.
Enter the full PITI payment: principal, interest, property taxes and homeowners insurance. Lenders count the whole housing payment in the front-end ratio, so a principal-and-interest figure understates it, sometimes by several percentage points.
Because the non-housing debts are doing the damage. If housing is 24% of income but total debts are 48%, the mortgage is affordable and the car, student and card payments are the problem. Paying off the smallest required payments first moves the back-end ratio fastest.
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References
- Consumer Financial Protection Bureau. What is a debt-to-income ratio? Ask CFPB. Accessed October 23, 2026.
- Consumer Financial Protection Bureau. Debt-to-income calculation worksheet, Your Money, Your Goals toolkit. Accessed October 23, 2026.
- Consumer Financial Protection Bureau. What is a qualified mortgage? Ask CFPB. Accessed October 23, 2026.
- Internal Revenue Service. Publication 936: Home Mortgage Interest Deduction. Accessed October 23, 2026.
- U.S. Department of Housing and Urban Development. Find a housing counselor. Accessed October 23, 2026.
- Freddie Mac. Am I financially prepared to take out a home loan? My Home by Freddie Mac. Accessed October 23, 2026.
- Consumer Financial Protection Bureau. Owning a Home: tools and resources for home buyers. Accessed October 23, 2026.