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Biweekly Mortgage Calculator
Sign up to favourite this calculatorCompare a standard monthly repayment mortgage with a biweekly payment illustration. A biweekly plan makes 26 half-payments a year—equivalent to 13 monthly-payment amounts—when extra amounts are applied to the mortgage balance.
Estimated earlier repayment with biweekly payments
The illustration makes 26 half-payments a year, equal to 13 monthly-payment amounts.
Annual amount modeled: £43,146 with monthly repayments and £46,741 with the biweekly illustration.
| Metric | Monthly repayments | Biweekly illustration |
|---|---|---|
| Payment amount | £3,595.49 per month | £1,797.74 every two weeks |
| Payments per year | 12 | 26 half-payments |
| Amount paid each year | £43,146 | £46,741 |
| Estimated payoff time | 25 years | about 21 years 4 months |
| Estimated total interest | £478,646 | £397,715 |
| Interest difference | — | £80,931 less interest in this illustration |
| Year | Monthly balance | Biweekly balance | Monthly interest | Biweekly interest | Balance difference |
|---|---|---|---|---|---|
| 1 | £588,070 | £584,330 | £31,216 | £31,072 | £3,740 |
| 2 | £575,498 | £567,818 | £30,574 | £30,229 | £7,680 |
| 3 | £562,250 | £550,417 | £29,898 | £29,341 | £11,833 |
| 4 | £548,290 | £532,081 | £29,185 | £28,405 | £16,209 |
| 5 | £533,578 | £512,758 | £28,435 | £27,419 | £20,820 |
| 6 | £518,076 | £492,396 | £27,643 | £26,379 | £25,680 |
| 7 | £501,740 | £470,939 | £26,810 | £25,284 | £30,801 |
| 8 | £484,525 | £448,328 | £25,931 | £24,130 | £36,197 |
| 9 | £466,384 | £424,501 | £25,005 | £22,914 | £41,883 |
| 10 | £447,268 | £399,393 | £24,030 | £21,633 | £47,875 |
| 11 | £427,123 | £372,934 | £23,001 | £20,282 | £54,190 |
| 12 | £405,896 | £345,052 | £21,918 | £18,859 | £60,844 |
| 13 | £383,526 | £315,671 | £20,776 | £17,360 | £67,856 |
| 14 | £359,954 | £284,709 | £19,573 | £15,780 | £75,245 |
| 15 | £335,113 | £252,082 | £18,305 | £14,115 | £83,031 |
| 16 | £308,937 | £217,701 | £16,970 | £12,360 | £91,236 |
| 17 | £281,353 | £181,470 | £15,562 | £10,511 | £99,883 |
| 18 | £252,285 | £143,291 | £14,078 | £8,562 | £108,994 |
| 19 | £221,654 | £103,059 | £12,515 | £6,509 | £118,596 |
| 20 | £189,376 | £60,662 | £10,867 | £4,345 | £128,714 |
| 21 | £155,361 | £15,986 | £9,132 | £2,065 | £139,376 |
| 22 | £119,518 | £0 | £7,302 | £161 | £119,518 |
| 23 | £81,746 | Repaid | £5,374 | Repaid | £81,746 |
| 24 | £41,944 | Repaid | £3,343 | Repaid | £41,944 |
| 25 | £0 | Repaid | £1,202 | Repaid | £0 |
Estimated mortgage balance: monthly vs biweekly payments
The dark line shows the monthly repayment schedule. The orange line shows the biweekly illustration, assuming every biweekly half-payment is applied to the mortgage balance.
For exact annual figures, view the Breakdown tab.
| Metric | Monthly repayments | Biweekly illustration |
|---|---|---|
| Payment amount | £3,595.49 per month | £1,797.74 every two weeks |
| Payments per year | 12 | 26 half-payments |
| Amount paid each year | £43,146 | £46,741 |
| Estimated payoff time | 25 years | about 21 years 4 months |
| Estimated total interest | £478,646 | £397,715 |
| Interest difference | — | £80,931 less interest in this illustration |
Assumptions used
- Constant annual interest rate: 5.25%
- Original mortgage term: 25 years
- Standard monthly repayment calculated from the repayment formula
- Biweekly payment: half the monthly repayment every two weeks
- 26 biweekly payments a year, equal to 13 monthly-payment amounts
- Biweekly interest modeled with a compounding-consistent two-week rate
- No lender fees, payment-holding practices, early-repayment charges, rate changes, overpayment allowances or lender-specific rules included
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Assumptions and limits
- An estimate from the numbers you entered, for guidance only. It is not financial, tax or medical advice.
- Calculator version 1, last updated 25 October 2026.
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How to use this calculator
Pick your currency, then enter the property price, your deposit, the annual interest rate and the mortgage term in whole years. The calculator works out the standard monthly repayment from those figures, then models a biweekly schedule that pays half that amount every two weeks.
The result shows how much sooner the modeled biweekly schedule clears the balance, the monthly and biweekly payment amounts, and the amount paid each year on each schedule. The Breakdown tab lists the annual balance and interest for both schedules, the Chart tab plots the two balance paths, and the Summary tab lists the assumptions used.
This is a neutral illustration, not mortgage advice. It does not recommend a payment plan, promise savings, assess affordability, predict whether a lender will accept biweekly payments, calculate fees or early-repayment charges, or forecast interest rates.
What do I need to enter?
- Property price — what the home costs, before any deposit. Must be above zero and at most 100,000,000.
- Deposit — the cash you put in. The loan is the price minus this, so it must be zero or more and below the price.
- Annual interest rate — the yearly rate, 0% to 100%, held fixed for the whole term.
- Mortgage term — whole years from 1 to 50. It sets the standard monthly repayment that the biweekly schedule is built from.
What do the results show?
- Estimated earlier repayment with biweekly payments — how much sooner the biweekly schedule clears the balance, or a note that the times are about the same.
- Payment amount and Payments per year — the monthly repayment against half that amount paid 26 times a year.
- Amount paid each year — the yearly total on each schedule.
- Estimated payoff time — how long each schedule takes to reach a zero balance.
- Estimated total interest and Interest difference — the interest each schedule costs, and how much less the biweekly one costs.
- Breakdown, Chart and Summary tabs — the year-by-year balance and interest for both schedules, a line chart of the two balances, and the assumptions used.
How biweekly mortgage payments are calculated
The calculator first works out the standard monthly repayment from the loan amount, annual interest rate and mortgage term. It then models payments of half that monthly amount every two weeks, using 26 payment periods a year.
- P — loan amount, the property price minus the deposit
- r — the annual interest rate you enter, as a decimal (5.25% is 0.0525)
- T — the mortgage term in whole years
- im = r ÷ 12 — the monthly periodic interest rate
- nm = 12 × T — the number of monthly payments in the term
- M — the standard contractual monthly repayment
- B = M ÷ 2 — the modeled biweekly payment
- nb = 26 × T — the number of biweekly payments in the term
- ib — the modeled compounding-consistent two-week periodic rate
- Qt — the balance remaining at the end of period t, starting from Q₀ = P
M = P × im(1 + im)ⁿᵐ ÷ ((1 + im)ⁿᵐ − 1)
- P = property price − deposit
- im = r ÷ 12
- nm = 12 × T
- If r = 0, M = P ÷ nm
- B = M ÷ 2
- 26 × B = 13 × M
ib = (1 + r ÷ 12)¹² ⁄ ²⁶ − 1
- biweekly interestₜ = Qₜ₋₁ × ib
- biweekly paymentₜ = min(B, Qₜ₋₁ + biweekly interestₜ)
- Qₜ = Qₜ₋₁ − (biweekly paymentₜ − biweekly interestₜ)
For each period, interest is charged on the outstanding balance, and the payment is reduced on the final period so the balance cannot go below zero. The monthly schedule uses imover 12 periods a year; the biweekly schedule uses ib over 26 periods a year. The annual figures shown in the table and chart are the raw period-level results aggregated into schedule years.
The biweekly periodic rate is a compounding-consistent illustration. Mortgage lenders and servicers can use different interest-calculation and payment-processing methods, so actual lender figures may differ.
At a 0% interest rate, M is simply P ÷ nm, both schedules have no interest, and the biweekly schedule can still finish earlier because 26 half-payments add up to 13 monthly-payment amounts a year.
Selecting a currency changes the labels and number formatting only. It does not convert amounts using exchange rates.
Biweekly versus twice-monthly payments
Biweekly means every two weeks: 26 half-payments a year. Twice-monthly payments are 24 half-payments a year and normally equal 12 monthly payments. This calculator models a biweekly schedule, not a twice-monthly schedule.
Other ways to pay off a mortgage faster
A biweekly schedule is one way to pay the equivalent of an extra monthly payment each year. The Mortgage Calculator with Extra Payments models a chosen regular or one-off overpayment instead, and the 15 vs 30 Year Mortgage Calculator compares choosing a shorter term outright.
Frequently asked questions
What is a biweekly mortgage payment?
A biweekly mortgage payment is half the standard monthly repayment, paid every two weeks instead of once a month. Because a year contains 26 two-week periods, a biweekly schedule makes 26 half-payments — the same as 13 full monthly-payment amounts. This calculator models that schedule and compares it with a standard monthly repayment mortgage. It is an illustration of the arithmetic, not a payment plan offered by a lender.
Why are there 26 biweekly payments in a year?
There are 52 weeks in a year, and 52 divided by 2 is 26, so paying every two weeks means 26 payments a year. Twelve of those 26 half-payments cover the equivalent of six monthly payments; the remaining 14 cover another seven — so 26 half-payments add up to 13 monthly-payment amounts, one more than the 12 made on a monthly schedule.
How is biweekly different from twice-monthly?
Biweekly means every two weeks, which is 26 payments a year. Twice-monthly (semi-monthly) means twice each calendar month — on the 1st and 15th, for example — which is 24 payments a year and normally adds up to exactly 12 monthly payments. A twice-monthly schedule pays the same total per year as a monthly one; a biweekly schedule pays the equivalent of one extra monthly payment. This calculator models a biweekly schedule, not a twice-monthly schedule.
Why does the annual amount differ from monthly repayments?
On a monthly schedule you make 12 payments of M, so you pay 12M in a year. On the modeled biweekly schedule you make 26 payments of M ÷ 2, so you pay 26 × (M ÷ 2) = 13M in a year. The extra 13M − 12M = M is one whole monthly-payment amount. The modeled difference in payoff time and interest comes from paying that extra amount each year, not from the change in payment timing on its own.
Does my lender apply biweekly payments immediately?
Not necessarily. Some lenders and servicers credit each half-payment to the mortgage balance as it arrives; others hold half-payments in a separate account and only apply a full monthly payment once both halves are received, which changes the interest effect. Some offer a formal biweekly programme, sometimes for a fee, and some do not accept biweekly payments at all. This calculator assumes each biweekly payment is applied to the balance when made. Check your mortgage offer and lender terms for how your payments would actually be handled.
Why might my lender’s figures differ?
The calculator uses one constant interest rate and a compounding-consistent two-week periodic rate. Real lenders use their own day-count and rounding conventions, may calculate interest daily or monthly, and may apply payments on set dates rather than immediately. Your rate is also likely to change when a fixed, tracker or discounted period ends. Treat the output as a rough illustration of the arithmetic, not a statement of what your lender will do.
Are fees or early-repayment charges included?
No. The illustration excludes arrangement and product fees, any charge for a lender’s biweekly programme, early-repayment charges, overpayment allowances, insurance, taxes and other costs. Some mortgages limit how much you can overpay in a year or charge an early-repayment charge for clearing the balance early, and paying the equivalent of 13 monthly payments a year is a form of overpayment. Your mortgage offer and lender’s rules determine whether that applies.
Does changing currency convert the mortgage amount?
No. Selecting a currency changes the currency symbol and number formatting on every field and result and nothing else. The property price, deposit, loan amount, payments, schedule and payoff durations keep the same nominal numbers — 600,000 stays 600,000 whether it is shown as pounds, dollars or euros. There is no exchange-rate conversion.
Last updated 25 October 2026.