Mortgage Calculator
A mortgage is typically the largest loan most people ever take. Understanding your full monthly payment — including principal, interest, property tax, and home insurance — helps you budget accurately and avoid financial surprises.
This calculator computes the monthly payment based on: home price, down payment percentage, interest rate, term, monthly property tax, and home insurance.
Under an illustrative assumption: home price 3.000.000.000 VND, 20% down (600.000.000 VND), borrowing 2.400.000.000 VND at 8%/year for 25 years — principal+interest payment = 18.523.589 VND/month. Adding tax (2.000.000) and insurance (1.500.000): total monthly cost = 22.023.589 VND. Total interest over 25 years: 3.157.076.779 VND.
The mortgage formula
Monthly payment (principal + interest)
M = L × r / (1 − (1+r)^−n)
| Symbol | Meaning |
|---|---|
| L | Loan amount = 3.000.000.000 − 600.000.000 = 2.400.000.000 VND |
| r | Monthly rate = 8% ÷ 12 ÷ 100 = 0.6667% |
| n | Total months = 25 × 12 = 300 |
| M | Monthly payment = 18.523.589 VND |
Down payment
Down payment = Home price × down % = 3.000.000.000 × 20% = 600.000.000 VND
Total monthly cost
Total = M + Tax + Insurance = 18.523.589 + 2.000.000 + 1.500.000 = 22.023.589 VND
Total interest over the term
Total paid = M × n = 18.523.589 × 300 = 5.557.076.779 VND Total interest = 5.557.076.779 − 2.400.000.000 = 3.157.076.779 VND
Impact of down payment
20% down: borrow 2.400.000.000 → 18.523.589/month 10% down: borrow 2.700.000.000 → 20.839.038/month (2.315.449 more/month)
Model limitations
The tool assumes a fixed rate and does not include closing costs, notary fees, or PMI (mortgage insurance when down payment < 20%).
Worked example: Home 3.000.000.000, 20% down, 8%/year, 25 years
| Metric | Value |
|---|---|
| Home price | 3.000.000.000 VND |
| Down payment (20%) | 600.000.000 VND |
| Loan amount | 2.400.000.000 VND |
| Monthly P+I | 18.523.589 VND |
| Monthly property tax | 2.000.000 VND |
| Monthly insurance | 1.500.000 VND |
| Total monthly cost | 22.023.589 VND |
| Total paid (P+I) | 5.557.076.779 VND |
| Total interest | 3.157.076.779 VND |
Term comparison
| Term | Monthly P+I | Total interest |
|---|---|---|
| 15 years | 22.935.650 | 1.728.417.004 |
| 25 years | 18.523.589 | 3.157.076.779 |
Frequently asked questions
How much down payment do I need for a mortgage?
Typically 10-30% of the home price. A 20% down payment (600.000.000 VND) reduces the loan to 2.400.000.000 VND with a monthly payment of 18.523.589 VND. Lower down payment means more borrowing and higher payments.
What does the total monthly cost include?
It includes: principal+interest (18.523.589), property tax (2.000.000), and home insurance (1.500.000). Total 22.023.589 VND/month. Some locations also have HOA fees or PMI.
How does a 15-year vs 25-year term compare?
15 years: 22.935.650/month, total interest 1.728.417.004. 25 years: 18.523.589/month (lower), total interest 3.157.076.779 (higher by 1.428.659.775).
Fixed vs adjustable rate mortgage?
A fixed rate (8% in the example) stays the same throughout the term — you know exactly what you pay each month. An adjustable rate tracks the market — it may start lower but carries the risk of increasing. This calculator assumes a fixed rate.
What is PMI and when do I pay it?
PMI (Private Mortgage Insurance) is required when your down payment is below 20%. At 20% down (≥20%), no PMI is needed. At 10% down, banks typically require PMI of ≈0.5-1% of the loan per year.
Is there a penalty for early repayment?
It depends on the lender. Some allow penalty-free prepayment; others charge 1-3% of the prepaid amount during the first 1-3 years. Always ask about prepayment terms before signing.