Mortgage Payoff Calculator (Extra Payment)
If you are a foreigner who has financed a home in Vietnam, your mortgage is almost certainly denominated in Vietnamese dong and amortised over 15–25 years. Over that long horizon the interest you pay can rival or exceed the original principal — which is precisely why prepaying principal is one of the highest-certainty returns available to you. Every extra dong you put toward principal each month permanently removes the future interest that dong would have generated, shortening both the loan term and the total interest at the same time. The calculator above simulates this month by month: enter the loan amount, rate, term and a monthly extra payment, and it reports how many months you save and how much interest you avoid.
Consider the worked example: a 2.000.000.000 VND loan over 20 years at an illustrative 10%/year carries a level payment of 19.300.433 VND per month. Add 5.000.000 VND a month toward principal and the loan is fully repaid in 11 years 8 months instead of 20 years — 100 months sooner — cutting total interest by roughly 1.241.495.363 VND. That saving comes purely from discipline, with no need to renegotiate your rate.
Two Vietnam-specific cautions matter before you act. First, Vietnamese mortgage rates are typically floating after a promotional period: lenders fix a low teaser rate for the first 6–24 months, then reset it as a "reference rate plus margin" that moves over the life of the loan — so the 10%/year here is an illustrative assumption to demonstrate the mechanics, not a rate you are guaranteed. Second, Vietnamese loan contracts often charge an early-prepayment penalty (phí phạt trả nợ trước hạn), frequently a percentage of the amount prepaid during the early years. Because these terms vary by bank, FiMo does not state a specific penalty figure — you must read your own contract and net any penalty against the interest saved below.
How the calculator works
The level monthly payment
For a fully-amortising loan (declining balance, equal payments), the monthly payment is:
M = P × r / (1 − (1 + r)^−n)
| Symbol | Meaning |
|---|---|
| M | Level payment per month |
| P | Original loan principal |
| r | Monthly rate = annual rate ÷ 12 (10%/year → 0.8333%/month) |
| n | Total number of monthly payments (20 × 12 = 240) |
For a 2.000.000.000 VND loan at 10%/year over 20 years, M = 19.300.433 VND/month. Paid on schedule for the full 20 years, total interest is M × n − P = 2.632.103.896 VND.
Adding extra principal each month
The tool simulates each month directly: the month's interest is balance × r, and the rest of the payment — M plus your extra amount — reduces principal. Because the balance falls faster, the next month's interest is smaller, so a growing share of each payment attacks principal. The loop ends when the balance reaches zero. Months saved = n − actual months, and interest saved = baseline total interest − total interest with extra payments.
Why early extra payments beat late ones
Early in the loan the outstanding balance is large, so interest makes up most of each payment. Prepaying principal then erases the future interest on that principal for the entire remaining life of the loan. The same total of extra payments concentrated in the first five years saves far more interest than the same amount spread evenly or paid near the end.
What the model leaves out
It assumes a constant rate for the whole term, whereas Vietnamese home-loan rates usually float after the promotional period — treat the output as a scenario, not a quote. It also excludes any prepayment penalty: if your contract imposes one, subtract your estimated penalty from the interest saved to find the true net benefit. Cross-check this tool with FiMo's loan/amortisation calculator, its refinance calculator, and its DTI/LTI affordability tool when weighing how aggressively to prepay.
Worked example: 2.000.000.000 VND loan, illustrative 10%/year, 20 years
Illustrative assumptions: a constant 10%/year rate (real VND mortgages usually float after a promo period), equal principal-and-interest payments, no prepayment penalty applied.
| Metric | On schedule | With 5.000.000 VND/month extra |
|---|---|---|
| Monthly payment | 19.300.433 | 24.300.433 |
| Payoff time | 20 years | 11 years 8 months |
| Total interest | 2.632.103.896 | 1.390.608.533 |
| Interest saved | — | 1.241.495.363 |
A modest 5.000.000 VND extra each month clears the loan 100 months early (about 8.3 years) and avoids up to 1.241.495.363 VND of interest — substantially more than the 700.000.000 VND of extra payments you actually made.
How much you save by how much you prepay
Same 2.000.000.000 VND loan / 10%/year / 20 years; a larger extra payment compresses both the term and the interest more sharply:
| Extra per month | Payoff time | Interest saved |
|---|---|---|
| 2.000.000 | 15 years 4 months | 716.974.292 |
| 5.000.000 | 11 years 8 months | 1.241.495.363 |
| 10.000.000 | 8 years 6 months | 1.661.962.909 |
These figures exclude any prepayment penalty. If your contract charges one during the early years, deduct your estimated penalty from the interest saved to get the net gain — and consider prepaying harder once that penalty window has passed.
Frequently asked questions
How much interest do extra payments save on a VND mortgage?
It depends on the loan size, rate and extra amount. On a 2.000.000.000 VND loan at an illustrative 10%/year over 20 years, paying 5.000.000 VND extra a month saves about 1.241.495.363 VND in interest and clears the loan 100 months early. Enter your own loan figures for an accurate result, and remember to subtract any prepayment penalty your contract imposes.
How much extra should I pay each month?
There is no fixed answer — it depends on your cash flow. On the same 2.000.000.000 VND / 10%/year / 20-year loan: 2.000.000 VND extra saves 716.974.292 VND; 5.000.000 VND saves 1.241.495.363 VND; 10.000.000 VND saves 1.661.962.909 VND. Larger extras save more, but do not drain your safety net — keep 3–6 months of expenses in reserve before accelerating repayment.
What is the early-prepayment penalty and should I worry about it?
Many Vietnamese home-loan contracts include an early-prepayment penalty (phí phạt trả nợ trước hạn) — a fee the bank charges when you pay above schedule or settle early, usually a percentage of the amount prepaid and higher in the early years. The amount varies by bank and by contract, so FiMo does not quote a specific figure; you must read your own loan terms. The right test is to subtract your estimated penalty from the interest the tool says you would save, leaving the net benefit.
Is the 10% rate in these examples a real mortgage rate?
No. The 10%/year used throughout this page is an illustrative assumption chosen to keep the math easy to follow. Vietnamese mortgage rates typically float after a promotional period: a low fixed teaser rate for the first 6–24 months, then a reset to a "reference rate plus margin" that changes over time and varies by bank. Enter the rate from your own contract — and stress-test a higher rate to see what happens when the floating period kicks in.
Why are early extra payments more effective than later ones?
Early in the loan the outstanding balance is large, so interest makes up most of each payment. Prepaying principal then removes the future interest on that principal for the entire remaining life of the loan. The same total of extra payments made in the first five years saves far more than the same amount paid near the end — which is the quantitative case for starting to prepay as early as you can, ideally once any penalty window has passed.
Should I prepay the mortgage or invest the money instead?
It is a guaranteed return versus a risky expected return. Prepaying a loan at 10%/year is equivalent to a risk-free, after-tax 10%/year return, because you avoid that interest for certain. If you can reliably earn more than 10% after tax and accept the risk, investing may win; otherwise prepaying is the safer choice. Factor in the floating rate too: if your mortgage rate resets higher, the value of prepaying rises with it.
How does the calculator compute the monthly payment?
With the standard amortising formula M = P × r / (1 − (1 + r)^−n), where P is the loan amount, r the monthly rate (annual ÷ 12) and n the total number of months. Verifiable example: P = 2.000.000.000, r = 10%/12, n = 240 gives M = 19.300.433 VND/month. For the extra-payment path it simulates month by month until the balance hits zero, then compares total interest against the baseline schedule to report months and interest saved.