Debt-to-Income Calculator

What this calculator does

This debt-to-income calculator shows how much of your gross monthly income is already committed to debt payments and how much room remains before you cross your target ceiling.

It is useful before applying for a mortgage, personal loan, auto loan, or refinance because the ratio helps frame affordability and underwriting risk quickly.

The best use of the tool is not just to see the current ratio, but to compare your current position with the ratio you would carry after adding the next payment.

This page is built for users who need a defensible planning answer, not just quick arithmetic. It translates "Gross monthly income", "Housing payment", and "Other monthly debt payments" into "Current DTI", "Projected DTI", and "Remaining monthly debt capacity" so the trade-off is visible in one place instead of being hidden behind a single number.

How to use the debt-to-income calculator

1. Enter gross monthly income first, then add your current housing payment and other required debt payments.
2. Set the target DTI ceiling you want to stay under, then use Advanced options if you want to test a proposed new monthly payment.
3. Read current DTI and projected DTI together so you can see whether the new loan still leaves breathing room.
4. Start with "Gross monthly income", "Housing payment", and "Other monthly debt payments", then check whether the first output cards already answer your question. After that, add advanced assumptions such as "Proposed new monthly payment" only when they are real enough to change the decision.

Formula and methodology

Debt-to-income ratio equals required monthly debt payments divided by gross monthly income.

Projected ratio adds the proposed new monthly payment on top of the current required debt load.

Remaining monthly debt capacity shows how much more required debt payment fits under the selected ceiling before you cross it.

The model maps "Gross monthly income", "Housing payment", and "Other monthly debt payments" into "Current DTI", "Projected DTI", and "Remaining monthly debt capacity" using the formulas shown on the page. Keeping those relationships visible makes it easier to separate the core economics from the optional adjustments and to understand which assumption is actually moving the answer.

Worked example and practical context

A borrower earning 6,200 per month with 2,100 of existing debt payments is already using a meaningful share of gross income before adding anything new.

If the next proposed payment pushes the projected ratio near the target ceiling, the monthly payment may still be technically possible but financially tight.

How to interpret the results

Current DTI shows your starting position. Projected DTI shows whether the next loan or housing payment pushes the structure into a riskier range.

Remaining monthly debt capacity is often the most practical output because it frames how much space is left before the target ceiling is breached.

Read "Current DTI" first, then use the other summary cards, the chart, and the detailed table to judge short-term affordability and long-term borrowing cost. In most finance decisions, the best option is the one that stays strong across the full picture, not just the one with the most attractive first number.

Common mistakes to avoid

• Using net income instead of gross income when comparing against lender-style DTI thresholds.
• Leaving out required housing costs or minimum debt payments.
• Treating a lender ceiling as the same thing as a comfortable personal cash-flow ceiling.

Key terms

Debt-to-income ratio

The share of gross monthly income already committed to required debt payments.

Debt capacity

The monthly payment room available before you cross a target DTI ceiling.