Debt To Income Calculator
Calculate the front-end and back-end debt-to-income ratios lenders use, and see exactly how much borrowing headroom remains.
Debt To Income Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: Debt-to-income ratio is total monthly debt payments divided by gross monthly income. Lenders look at two: front-end covers housing only and should stay near 28%, while back-end covers all debt and should stay near 36%, with Qualified Mortgage rules allowing up to 43%.
Formula
Both ratios use gross income, before tax and deductions, because that is the convention in mortgage underwriting.
Worked Example
- Total the housing cost. Full PITI of $2,703.75.
- Total other debt. $400 car + $250 student = $650.00.
- Compute front-end. $2,703.75 ÷ $9,000 = 30.0%.
- Compute back-end. $3,353.75 ÷ $9,000 = 37.3%.
- Interpret. Above the 36% guideline but inside the 43% QM ceiling.
Analyst note. This borrower is $113.75 per month over the 36% guideline but has $516.25 of headroom to the 43% Qualified Mortgage ceiling. Clearing the $250 student payment would bring the back-end ratio to 34.5% and restore a comfortable margin.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Checking approval odds before applying
Lenders compute this before anything else, so knowing both ratios tells you the likely answer in advance. Convert the result into a price band with the Mortgage Affordability Calculator.
Working out which debt to clear first
Only the monthly payment matters to the ratio, not the balance. A small loan with a large payment hurts your ratio more than a large loan with a small one, which frequently inverts the intuitive payoff order.
Planning a purchase around existing obligations
The housing-allowed output shows exactly what remains for a mortgage after current debts. Price the resulting payment with the Mortgage Payment Calculator.
Methodology & Editorial Standards
Both ratios follow standard mortgage underwriting convention and are computed on gross monthly income before tax. The front-end ratio counts full housing cost including escrowed taxes, insurance and any HOA dues; the back-end ratio adds every recurring debt payment reported to credit bureaux. Only minimum required payments count, not the balances outstanding and not voluntary overpayments. Living expenses such as utilities, groceries, insurance premiums and childcare are excluded because lenders exclude them, even though they materially affect real affordability. Thresholds shown are the conventional 28/36 guidance and the 43% Qualified Mortgage ceiling; individual programmes extend to 50% with compensating factors. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Debt To Income Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is a good debt-to-income ratio?
Below 36% overall is comfortable, with housing below 28%. Between 36% and 43% is still approvable under Qualified Mortgage rules, and above 43% requires compensating factors such as large reserves or a high credit score.
What is the difference between front-end and back-end DTI?
Front-end counts only housing costs against income; back-end counts all recurring debt including housing. In this example they are 30.0% and 37.3% respectively, and lenders generally weight the back-end figure more heavily.
Does DTI use gross or net income?
Gross, before tax and deductions. This is why a 36% ratio feels tighter than it sounds: on net income it can easily represent 45% or more of what actually reaches your account.
Which debts count towards the ratio?
Minimum payments on credit cards, car loans, student loans, personal loans, other mortgages and court-ordered obligations such as alimony or child support. Utilities, insurance, groceries and childcare are excluded.
Does paying down a balance improve my DTI?
Only if it reduces or removes the monthly payment. Halving a credit card balance lowers the minimum payment and helps; halving a fixed instalment loan balance usually does not change the payment at all until it is cleared entirely.
Which debt should I clear first to improve my ratio?
The one with the highest monthly payment relative to its remaining balance, which is often a nearly finished car loan. That is frequently the opposite of the interest-optimal order, so decide which goal you are pursuing.
What is the 43% rule?
The Qualified Mortgage standard, above which a loan loses certain legal protections for the lender. It functions as a practical ceiling for most conforming lending, though portfolio lenders and government programmes go higher.
Can I get a mortgage with a high DTI?
Yes, particularly through FHA and VA programmes, which routinely approve ratios above 43% with compensating factors. The question is whether you should: a high ratio leaves little capacity to absorb any financial shock.
Do student loans in deferment count?
Usually yes. Most programmes impute a payment — commonly 0.5% to 1% of the outstanding balance monthly — even when nothing is currently due, because the obligation will resume.
How do lenders treat variable income?
By averaging the most recent two years and discounting anything without that history. Bonus and commission income needs a documented track record before it counts towards the income side of the ratio.
Does a co-borrower improve the ratio?
It can, because both incomes and both debt loads are combined. It helps when the co-borrower brings more income than debt, and hurts when they do not, so the arithmetic must be checked rather than assumed.
Why does my housing payment count the full PITI?
Because taxes, insurance and HOA dues are mandatory costs of the property. Counting only principal and interest would understate the obligation by 20 to 25% and defeat the purpose of the ratio.
Is this debt to income calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.
Which currency does it use?
Amounts display in US$ accounting format, but the underlying mathematics is currency-agnostic. The result is identical in any currency, so simply read the figures in your own.
Why does a result show an em-dash?
An em-dash indicates the calculation is not defined for the inputs given — typically a division by zero or a value outside the valid domain. We show a dash rather than a misleading number.
How do I report an error?
Email apexconverter.praxiscalc@gmail.com with the tool URL, your exact inputs, the output received and the output you expected. Verified mathematical errors are patched within 72 hours.