Methodology & data sources
Every calculator on this site uses the same open formula engine in your browser and at build time. This page documents the formulas, fee schedules and data behind each number, and what the estimates leave out.
Monthly principal & interest
Fixed-rate payments use the standard amortization formula:
M = P × r(1 + r)n ÷ [(1 + r)n − 1]
where P is the loan amount (including any financed FHA upfront premium or VA funding fee), r the annual rate ÷ 12 and n the number of monthly payments. The amortization schedule applies each payment to interest on the outstanding balance first, and the final payment is adjusted so the balance ends at exactly $0. See the CFPB's explanation: How do mortgage lenders calculate monthly payments?
Monthly escrow adds property tax (home price × effective tax rate ÷ 12), homeowners insurance (annual premium ÷ 12) and any HOA dues.
Conventional & jumbo PMI
With less than 20% down, private mortgage insurance is estimated from the loan-to-value ratio. PMI rates are mid-range estimates for a 720+ FICO borrower; actual premiums are priced by the mortgage insurer. PMI is removed in the schedule when the balance reaches 80% of the original home price.
| Loan-to-value | Annual PMI estimate |
|---|---|
| 80.01% – 85% | 0.46% |
| 85.01% – 90% | 0.72% |
| 90.01% – 95% | 0.96% |
| 95.01% – 97% | 1.30% |
| 97.01% – 100% | 1.50% |
Sources: CFPB — What is private mortgage insurance?; Homeowners Protection Act (PMI cancellation at 78–80% LTV)
FHA mortgage insurance (UFMIP & annual MIP)
An upfront premium of 1.75% of the base loan is added to the loan balance. The annual premium is charged monthly on the average scheduled balance of each loan year:
| Term | Base loan | LTV | Annual MIP |
|---|---|---|---|
| More than 15 years | ≤ $726,200 | ≤ 95% | 0.50% |
| More than 15 years | ≤ $726,200 | > 95% | 0.55% |
| More than 15 years | > $726,200 | ≤ 95% | 0.70% |
| More than 15 years | > $726,200 | > 95% | 0.75% |
| 15 years or less | ≤ $726,200 | ≤ 90% | 0.15% |
| 15 years or less | ≤ $726,200 | > 90% | 0.40% |
| 15 years or less | > $726,200 | ≤ 78% | 0.15% |
| 15 years or less | > $726,200 | > 78% | 0.40% |
| 15 years or less | > $726,200 | > 90% | 0.65% |
MIP lasts 11 years when the original LTV is 90% or less, and for the life of the loan otherwise. The minimum down payment is 3.5%.
Sources: HUD Mortgagee Letter 2023-05 (annual MIP schedule); HUD — FHA single family housing policy handbook 4000.1
VA funding fee
VA loans carry no monthly mortgage insurance. The one-time funding fee depends on down payment and whether this is your first use of the benefit; it can be financed or paid at closing. Veterans receiving VA disability compensation, and certain surviving spouses and Purple Heart recipients, are exempt from the funding fee.
| Down payment | First use | Subsequent use |
|---|---|---|
| 0% – under 5% | 2.15% | 3.30% |
| 5% – under 10% | 1.50% | 1.50% |
| 10% or more | 1.25% | 1.25% |
Sources: VA — Funding fee and closing costs
APR
APR is the annual rate at which the present value of scheduled principal, interest and mortgage insurance equals the amount financed (the loan minus prepaid finance charges such as the FHA upfront premium or VA funding fee). Lender origination fees and points are not included, so a lender's Loan Estimate APR will usually be higher.
Loan limits & jumbo classification
A loan is treated as jumbo when it exceeds the county's FHFA one-unit conforming limit. For 2026 the baseline is $832,750 and the high-cost ceiling is $1,249,125 (Alaska, Hawaii, Guam and the U.S. Virgin Islands have higher statutory limits). County data: FHFA 2026 Conforming Loan Limit Values (one-unit).
FHA limits are shown as a range from the national floor ($541,287, 65% of the conforming baseline) to the county conforming limit. Confirm your county's exact FHA limit with HUD FHA Mortgage Limits lookup.
Default rates & local data
| Data | Source | As of |
|---|---|---|
| 30-year and 15-year fixed rate defaults (7.03% / 6.42%) | Freddie Mac Primary Mortgage Market Survey (PMMS) | September 24, 2026 |
| Default home price (typical home value by state, U.S. $368,697) | Zillow Home Value Index (ZHVI), typical home value, all homes | August 31, 2026 |
| Conforming loan limits by county | FHFA | 2026 |
| Effective property tax rate by state | Effective statewide property tax rate (Tax Foundation, 2026 projections) | 2026 |
| Average homeowners insurance by state | Average annual homeowners premium, $300K dwelling / $1K deductible (industry survey averages) | 2026 |
Rates change weekly. The default rate is a national average for borrowers with strong credit and is shown for education only; your quoted rate will differ.
Limitations
- Property tax and insurance use statewide averages; county and city rates vary widely.
- PMI rates are estimates — actual premiums depend on credit score, insurer and loan features.
- Closing costs, points, origination fees and prepaid items are not included.
- Adjustable-rate, interest-only and USDA loans are not modelled.