Every extra dollar goes straight to principal, so accelerating payments early in the loan saves the most interest. Before you start, check for prepayment penalties and compare with the return you could earn by investing the money.
How to use the Mortgage Acceleration Calculator
- Loan amount
- Mortgage term
- Interest rate
- Type of acceleration
- Extra payment per period
- Due date of the first payment
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the loan amount, term and rate, choose the acceleration type and any extra payment.
Tips
- Get a written loan estimate and compare the APR, not just the interest rate.
- Include property tax, insurance, HOA fees and maintenance in your monthly budget.
- A larger down payment lowers the payment and can remove mortgage insurance.
- Rates change daily – use a current quote for the most accurate result.
Common mistakes to avoid
- Looking only at the monthly payment instead of the total cost of the loan.
- Forgetting closing costs and fees.
- Assuming home prices always rise.
Inputs explained
| Field | What to enter |
|---|---|
| Loan amount | Amount in your currency |
| Mortgage term | Units: years, months |
| Interest rate | In % |
| Type of acceleration | Choose one: Monthly with overpayment, Accelerated bi-weekly, Accelerated weekly |
| Extra payment per period | Amount in your currency |
| Due date of the first payment | A date |
What each result means
- Regular monthly payment = pmt([Interest rate]÷1200, [Mortgage term], [Loan amount])
- Number of accelerated payments = nper([Rate per payment], [Accelerated payment], [Loan amount])
- Accelerated payoff time = [Number of accelerated payments]÷[Payments per year]
- Payoff date = [Due date of the first payment] + [Number of accelerated payments]×365.25÷[Payments per year]
- Total interest without acceleration = [Regular monthly payment]×[Mortgage term] – [Loan amount]
- Total interest with acceleration = [Accelerated payment]×[Number of accelerated payments] – [Loan amount]
- Interest saved = [Total interest without acceleration] – [Total interest with acceleration]
- Years saved = [Mortgage term]÷12 – [Accelerated payoff time]
Example values
How the main result changes when Loan amount changes and everything else stays at the example values above:
| Loan amount | Interest saved |
|---|---|
| 150,000 | 79,916.68 |
| 225,000 | 94,106.82 |
| 300,000 | 103,449.99 |
| 375,000 | 110,086.94 |
| 450,000 | 115,051.67 |
| 600,000 | 121,992.18 |
Formula
Regular payment M = pmt(i, n, P)Monthly with overpayment: nper(i, M + extra, P)Accelerated bi-weekly: M ÷ 2 every two weeks; accelerated weekly: M ÷ 4 every weekWorked example
Inputs — Loan amount: $300,000; Mortgage term: 30 years; Interest rate: 6.5 %; Type of acceleration: Monthly with overpayment; Extra payment per period: $200; Due date of the first payment: 2026-11-24.
Results — Regular monthly payment = $1,896.20; Accelerated payment = $2,096.20; Number of accelerated payments = 276; Accelerated payoff time = 23 years; Payoff date = Thu, December 2, 2049; Total interest without acceleration = $382,633.47; Total interest with acceleration = $279,183.48; Interest saved = $103,449.99; Years saved = 7.
Frequently asked questions
How can I pay off my mortgage faster?
Extra monthly payments, accelerated bi-weekly payments or lump sums.
How much does $100 extra a month save?
On a $300,000 30-year loan at 6.5%, roughly 4–5 years and $60,000+ of interest.
Is paying off a mortgage early smart?
It's a guaranteed return equal to your rate; compare with investing and keep an emergency fund.
What formula does the Mortgage Acceleration Calculator use?
Regular payment M = pmt(i, n, P).