Research question
How much of a monthly mortgage payment is insurance — homeowners insurance and, below 20% down, mortgage insurance — and how does that share change with the down payment?
Dataset
- A $500,000 home at 6.71% (PMMS), 1.1% property tax, $150/mo homeowners insurance.
- Down payments of 20%, 15%, 10% and 5% (full PITI model).
- Conventional PMI tiers from the TruePITI pricing matrix.
Methodology
- Compute full PITI for each down payment.
- Mortgage-insurance share = monthly MI ÷ total monthly payment.
- Hold rate, tax and homeowners insurance constant to isolate the MI effect.
Calculations
| Down | Mortgage ins. / mo | P&I / mo | Total / mo | MI share of total |
|---|---|---|---|---|
| 20% down | $0 | $2584 | $3192 | 0.0% |
| 15% down | $177 | $2745 | $3531 | 5.0% |
| 10% down | $281 | $2907 | $3796 | 7.4% |
| 5% down | $396 | $3068 | $4072 | 9.7% |
$500,000 home, 6.71%, 30-yr, 1.1% tax, $150/mo homeowners insurance.
Mortgage-insurance share of the monthly payment
Share of total monthly payment that is mortgage insurance.
20% down0.0%
15% down5.0%
10% down7.4%
5% down9.7%
Findings
- Homeowners insurance is a flat, down-payment-independent cost — it does not change with LTV.
- Mortgage insurance is the LTV-driven cost, and its share of the payment grows as the down payment shrinks.
- At 20% down there is no mortgage insurance, so insurance is only the homeowners premium.
Limitations
- Homeowners insurance varies widely by state (wind, hail, wildfire) — a flat $150/mo understates high-risk areas.
- MI reflects one credit band; actual MI varies by lender and insurer.
- Excludes flood/wind riders and HOA master policies.
Sources
Last updated & change history
Last updated: 2026-09-21
- 2026-09-21 — Initial study.