About dibobo

What dibobo does

dibobo is an independent collection of free U.S. mortgage planning tools maintained by Bobo, a web developer. It is not a lender, mortgage broker or financial advisory service. Amounts are in USD, and preset rates are examples rather than current offers. English and Spanish tools share the same calculation code.

How the calculations work

The mortgage calculator models fixed monthly principal-and-interest payments: M = P × r / [1 − (1 + r)^−n], with monthly rate r and number of payments n. At zero interest, M = P / n. The schedule charges monthly interest on the remaining principal, then applies principal and extra payments. The final payment is reduced to the amount still owed.

Taxes, insurance, PMI and HOA are separate inputs, not lender quotes. Property tax is estimated from the modeled home price, which may differ from the local assessed value. The PMI amount does not automatically establish eligibility or cancellation.

The refinance calculator assumes equal starting balances and upfront fees paid in cash. At a shared exit date it compares payments made plus the balance still owed, including fees for the new loan. This equals the difference in interest paid minus fees. It excludes financed costs, cash-out, investment returns and the time value of money.

The affordability calculator uses a 28/36 income-and-debt budgeting assumption, not a universal approval standard. Its estimate excludes PMI, repairs, closing costs and other living expenses. Actual lender limits and your comfortable budget may differ.

Checks and limitations

We check zero-interest loans, final payoff balances, extra payments, identical refinance offers, upfront-fee effects and comparisons before and after payoff. Browser checks cover English and Spanish results and narrow-screen layout. These checks reduce mistakes but do not guarantee that estimates match a lender’s exact rounding, payment timing or product terms.

Sources and corrections

Financial explanations link to primary sources such as the CFPB Loan Estimate explainer. Calculated examples are labeled with their assumptions. Publication does not imply professional financial review or lender endorsement.

If a result seems wrong, contact us with the page URL, non-sensitive example inputs, the result shown and the result you expected. Do not send account numbers, identity documents or other confidential financial details. We check reproducible issues and update affected explanations and dates.

Your information

Calculator inputs are processed in your browser, not uploaded by our tools. No account is required. See the privacy notice for hosting and contact information.

Methodology updated: September 28, 2026