Loan Principal from Monthly Payment Room
Set a share of income available for debt payments, then find room for a new payment. Converting that room into fixed-rate principal is a mathematical scenario, not a lender’s maximum approval amount.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
Numbers stay on your device. Nothing is sent to a server.
Include minimums on cards, auto loans, student loans, and other instalments. Do not include the new loan.
Common napkin caps sit near 36% or 43%. Programs vary.
How to use this tool
Enter monthly income, existing monthly debt, target DTI, annual rate and years in USD terms. Taxes, insurance and association charges are not added, so consider them when choosing a budget allowance.
Results and examples
New payment room is income × target ratio minus existing payments. Principal is the level-payment loan supported by that room; income left over has not had living expenses deducted.
Worked example
USD 6,000 income, USD 800 debt and a 30% allowance leave USD 1,000 monthly, supporting USD 120,000 at 0% over ten years.
Limitations
- Credit, collateral, taxes, insurance and lender overlays are excluded.
- Living costs can make actual affordability lower than this calculation.
Fields
| Field | Guidance and constraints |
|---|---|
| Gross monthly income | Accepted range: 0–10000000 · Input step: 50 |
| Existing monthly debts | Include minimums on cards, auto loans, student loans, and other instalments. Do not include the new loan. · Accepted range: 0–10000000 · Input step: 10 |
| DTI cap | Common napkin caps sit near 36% or 43%. Programs vary. · Accepted range: 1–80 · Input step: 0.5 |
| Annual interest rate | Accepted range: 0–50 · Input step: 0.01 |
| Term (years) | Accepted range: 1–40 · Input step: 1 |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
Is this a preapproval?
No. It is principal derived from your chosen payment allowance.
How is zero interest handled?
Monthly payment room is multiplied by total months.
Related tools
You do not need to start over. Continue with the tool that fits your next step.
