Calculator
Mortgage Calculator: Principal, Interest, Taxes, Insurance, and PMI
Estimate housing payments with mortgage principal, rate, term, taxes, insurance, and down payment assumptions.
Overview
Mortgage calculator: principal, interest, taxes, insurance, PMI
This calculator estimates the full monthly housing payment (PITI plus PMI) for a fixed-rate mortgage. It is meant for early affordability planning, not as a substitute for a lender’s Loan Estimate.
Mortgage estimate results
Inputs
What each field represents
Home price: the contract or expected purchase price. Down payment: cash to closing applied to principal. Rate: annual interest rate; APR if you want to include lender fees. Term: typically 30 or 15 years. Annual taxes and insurance: divided by 12 and added to the monthly payment. Monthly PMI: required on conventional loans with under 20% down (and on FHA loans as MIP, with different removal rules).
Formula
The amortization math
The principal-and-interest portion uses the standard amortization formula P = A · r ÷ (1 − (1 + r)−n) with r as the monthly rate and n as the number of monthly payments. Taxes, insurance, and PMI are added directly to the monthly figure to produce a planning estimate of the full payment.
Limits
What the calculator does not include
HOA dues, condo special assessments, supplemental property tax assessments in some states, flood insurance where required, and any state or municipal tax credits are not included. For a true line-item picture, request a Loan Estimate from at least three lenders; see the CFPB’s Loan Estimate guide.
FAQ
Common questions
Should I include taxes and insurance even if they are paid separately?
Yes. Whether your lender escrows or not, those costs come out of your household budget every month. The most honest affordability test treats them as part of the housing payment.
Does the calculator account for interest-only or ARM loans?
No. It assumes a fixed-rate fully-amortizing loan. Interest-only and adjustable-rate mortgages have different payment dynamics that this tool does not model.
How conservative should I be on rate and taxes?
Conservative. Pick a rate that gives you cushion if pricing moves before lock, and use the highest plausible local property-tax rate. Underestimating either is a common reason buyers feel stretched after closing.
Sources & Methodology
Where we pulled the numbers
- CFPB · Loan Estimate form — The standardized federal disclosure every lender must give within three business days.
- Federal Reserve · Mortgage rates (FRED) — 30-year fixed mortgage average, updated weekly by the Federal Reserve via Freddie Mac PMMS.
- HUD · FHA loan limits — FHA program rules, limits, and counseling resources.
This guide was created with AI-assisted drafting and human editorial review by Javi Pérez. Figures, examples, and explanations are checked against public sources including CFPB, the Federal Reserve, FDIC, BLS, FTC, and SEC where applicable. Content is reviewed quarterly. Javi Pérez is not a licensed financial advisor, CPA, CFP, loan officer, tax professional, or attorney. This content is educational only and does not replace advice from a qualified professional.
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