Biweekly vs Monthly Mortgage Calculator
Compare five ways to pay the same mortgage and see the difference between savings from more frequent payments and savings from paying extra principal.
Accelerated biweekly interest saved$89,344.81
- Standard monthly payment
- $1,896.20
- Regular biweekly payment
- $875.17
- Accelerated biweekly time saved
- 5 years 11 months
- Savings caused by payment timing alone
- $2,088.52
- Extra principal paid per year
- $1,896.20
Payoff comparison
| Schedule | Payment | Payoff time | Total interest | Interest saved | Time saved |
|---|---|---|---|---|---|
| Monthly | $1,896.20 | 30 years | $382,633.47 | $0.00 | 0 months |
| Semi-monthly | $948.10 | 29 years 11 months | $379,804.50 | $2,828.97 | 1 month |
| Regular biweekly | $875.17 | 29 years 11 months | $379,588.29 | $3,045.18 | 1 month |
| Accelerated biweekly | $948.10 | 24 years 1 month | $293,288.66 | $89,344.81 | 5 years 11 months |
| Monthly + one-twelfth extra | $2,054.22 | 24 years 2 months | $295,377.18 | $87,256.29 | 5 years 10 months |
Assumes a fixed rate, payments made at the end of each payment period, and principal-and-interest payments only.
Accelerated biweekly and monthly plus one-twelfth extra each pay the equivalent of 13 monthly payments per year.
How to use this calculator
- Enter the principal balance currently outstanding on the mortgage.
- Enter the fixed annual interest rate used for the remaining amortization.
- Enter the years remaining on the principal-and-interest repayment schedule.
- Review the table to compare payment size, payoff time, and interest for each schedule.
How monthly and biweekly mortgage payments are compared
The calculator first finds the level monthly principal-and-interest payment for the balance, fixed rate, and remaining amortization. It then runs a separate payment-by-payment amortization for each schedule. That matters because a payment made earlier reduces the balance on which later interest is calculated.
The standard monthly payment is:
M = P × r ÷ (1 − (1 + r)^−n)
- P is the current principal balance.
- r is the annual rate divided by 12.
- n is the remaining years multiplied by 12.
For each payment frequency, the calculator uses an equivalent period rate: i = (1 + r)^(12 ÷ f) − 1, where f is payments per year. It adds period interest to the balance, applies the scheduled payment, and reduces the last payment to the exact amount due. This preserves the effective annual rate implied by monthly compounding instead of simply dividing the monthly rate by 24 or 26.
Regular versus accelerated biweekly payments
Regular biweekly payments divide 12 monthly payments across 26 payments, so the annual amount is unchanged. Semi-monthly payments also add up to 12 monthly payments, but occur 24 times a year. Either can create a small saving in this model because principal is paid down sooner.
Accelerated biweekly payments are one-half of the monthly payment, made 26 times a year. That totals 13 monthly payments each year: one extra monthly payment of principal and interest. The table also includes a monthly payment plus one-twelfth extra. It pays the same nominal amount each year as accelerated biweekly, so the difference in their interest cost isolates the effect of payment timing.
What changes the result and what is left out
The balance, rate, and remaining amortization drive the result. A higher rate makes earlier payments more valuable, while a shorter remaining term leaves less time for timing or extra-principal savings to accumulate. The Financial Consumer Agency of Canada notes that larger payments can shorten the time to repay a mortgage and reduce interest.
This is a principal-and-interest model. It does not include escrow, property taxes, home insurance, mortgage insurance, fees, prepayment limits, changing rates, or lender-specific rounding. Some servicers hold a partial biweekly payment until they can post a full monthly installment, which can remove the timing benefit shown here.
Worked example
For a $300,000 balance at 6.5% with 30 years remaining, the standard monthly payment is $1,896.20. A regular biweekly payment is $875.17, which still totals 12 monthly payments in a year. An accelerated biweekly payment is $948.10, so 26 payments total 13 monthly payments.
The comparison table uses the full, unrounded payment amounts to calculate payoff time and interest. It shows the small difference created by paying on a biweekly schedule, then separates it from the much larger effect of the additional annual payment in the accelerated plan.
Common questions
What is the difference between biweekly and semi-monthly mortgage payments?
Biweekly means 26 payments each year, usually every other week. Semi-monthly means 24 payments each year, commonly two set dates per month. A regular version of either plan adds up to 12 monthly payments each year, although the dates can produce a small difference in interest.
Why does accelerated biweekly create one extra monthly payment each year?
An accelerated biweekly payment is half the monthly payment, but it is made 26 times a year. Twenty-six halves equal 13 whole monthly payments. The thirteenth payment is additional principal and interest beyond a normal 12-payment year.
Does regular biweekly actually pay a mortgage off faster?
It can, but the effect is usually modest because the annual payment amount is unchanged. In this calculator, regular biweekly payments lower the balance a little sooner than monthly payments. Your lender’s posting rules can change or eliminate that benefit.
Is paying one-twelfth extra each month equivalent to accelerated biweekly payments?
Both plans pay the equivalent of 13 monthly payments per year when the rate and payment remain fixed. They do not post principal on the same dates, so their interest can differ slightly. The table shows that timing-only difference separately.
Should escrow, taxes, and insurance be included in a biweekly payment?
No. This calculator uses principal and interest only. Ask your servicer how it handles tax, insurance, and mortgage-insurance deposits before splitting a total mortgage bill into partial payments.