A lender determines what it will offer after its own review. A calculator can answer a different question: what principal corresponds to a payment you choose? Neither income alone nor the figure below establishes eligibility.
Build the payment allowance before solving for principal
In this invented monthly cash budget, $4,000 take-home income minus $2,500 essentials, $700 existing debt payments and $500 reserve leaves $300. That is a planning allowance, not a promised payment or approval threshold. If income is variable, test lower-income months and irregular expenses.
What principal corresponds to that $300 allowance?
| Annual note rate | Term | Principal at $300/month | Net cash if5% withheld |
|---|---|---|---|
| 12% | 36 months | $9,032.25 | $8,580.64 |
| 12% | 60 months | $13,486.51 | $12,812.19 |
| 18% | 36 months | $8,298.21 | $7,883.30 |
| 18% | 60 months | $11,814.08 | $11,223.38 |
| 24% | 36 months | $7,646.65 | $7,264.32 |
| 24% | 60 months | $10,428.27 | $9,906.85 |
The inverse amortization formula is principal = payment × [1 − (1 + monthly rate)−months] / monthly rate. The net column multiplies principal by0.95. A withheld fee reduces cash received without reducing the balance being repaid. Extending the term allows more principal at the same installment but increases the number of payments.
How does this differ from DTI?
With hypothetical $5,000 gross monthly income and $700 existing monthly debts, adding $300 produces 20% DTI. That ratio uses gross income; it does not capture every living cost. The $300 cash allowance and 20% ratio describe this example only. Ask the lender which obligations, income records and criteria it uses.
What can change an actual offer?
Provider criteria, verified income, existing obligations, credit history, requested purpose, state availability and product limits may differ. Use the smaller of your actual need and a sustainable budget as a planning starting point. If no offer fits, reducing the expense or delaying it avoids pretending the calculator can guarantee more credit.
Reproduce another amount with the personal-loan calculator. Check requirements, income documentation and credit considerations. Use the DTI calculator alongside a take-home cash budget. The 420-scenario Loan Cost Index supplies comparable fee-free examples.
Related: affordability planning, net-proceeds fee examples, and official state lending resources.
Primary sources and model scope
The CFPB explains gross-income DTI and differing lender limits and interest rate versus fee-inclusive APR. Those sources support the definitions; the dollar figures on this page are BYL hypothetical calculations, not government recommendations. Sources checked October 23,2026.