How do biweekly payments save money?

By paying half the monthly payment every two weeks, you make 26 half-payments per year, which equals 13 full payments instead of 12. The extra payment each year goes directly to principal, lowering the balance faster and reducing the interest that accrues for the rest of the loan.

Does my lender support biweekly payments?

Not all lenders offer formal biweekly programs, and some charge $200–$400 to set them up. You can achieve the identical math for free by making one extra full payment per year, or by adding 1/12 of your monthly payment as additional principal each month through your lender's online portal.

How much time can I save?

On a 30-year mortgage, biweekly payments typically shave 4–6 years off the payoff and save 20–30% of total interest, depending on the loan amount and rate. Higher rates and longer terms produce larger savings; a low-rate 15-year mortgage sees a smaller benefit because there is less interest to save in the first place.

Is it better to pay biweekly or invest the difference?

It depends on the rate. A 3% mortgage compared against an expected 7% portfolio return favors investing the difference. A 7%+ mortgage compared against the same portfolio return is roughly a wash, and accelerating the mortgage has the advantage of guaranteed savings vs. variable market returns. Risk tolerance and your overall financial situation matter.

Can I switch from biweekly back to monthly?

Yes — biweekly is not a contractual change to the loan terms, just to the payment schedule. You can call the lender and switch back, or stop the voluntary extra principal payments at any time. Any extra principal already paid stays applied; it just reduces future interest.

Biweekly Mortgage Calculator

Compare biweekly vs monthly mortgage payments. Biweekly payments result in 26 half-payments (13 full payments) per year instead of 12, helping you pay off your mortgage years faster.

The biweekly mortgage payoff trick is simple. Instead of making one full mortgage payment each month, you pay half the payment every two weeks. Since there are 52 weeks in a year, you end up making 26 half-payments, which equals 13 full payments — one extra payment per year compared to the standard 12. That extra payment goes entirely to principal, which compounds the savings dramatically over the life of the loan.

On a typical 30-year mortgage, switching to biweekly payments shaves 4–6 years off the payoff timeline and saves tens of thousands of dollars in interest. The mechanism is the same as making any other extra principal payment: a smaller remaining balance accrues less interest in every subsequent month, so each "extra" dollar paid early saves several dollars of interest later.

This calculator compares the standard monthly schedule to the biweekly schedule on the same loan. The savings number is real, but the implementation matters. Some lenders charge enrollment fees for true biweekly programs (often $300–$400). You can achieve the same result for free by simply paying 1/12 of your monthly payment as extra principal each month, or by making one extra full payment per year. The math is what produces the savings — not the payment frequency itself.

Inputs

Loan Amount

Annual Interest Rate

Loan Term (Years)

Results

Interest Saved

$88,122

Time Saved

6 yrs 10 mo

Monthly Payment

$1,896

Biweekly Payment

$948

Total Interest Comparison

Balance Over Time

Yearly Balance Comparison

Year	Monthly Balance	Biweekly Balance
1	$296,646.82	$294,685.12
2	$293,069.08	$289,013.76
3	$289,251.73	$282,962.01
4	$285,178.72	$276,504.36
5	$280,832.93	$269,613.57
6	$276,196.10	$262,260.60
7	$271,248.73	$254,414.45
8	$265,970.03	$246,042.04
9	$260,337.81	$237,108.07
10	$254,328.38	$227,574.87
11	$247,916.49	$217,402.26
12	$241,075.18	$206,547.35

Last updated: May 25, 2026Reviewed by the CalcMountain editorial team

Formula

Standard monthly payment (amortization): M = L × [ r × (1 + r)^n ] / [ (1 + r)^n − 1 ] Where: L = Loan amount r = Monthly interest rate (annual rate ÷ 12) n = Total payments (years × 12) Biweekly equivalent: Each biweekly payment = M / 2 Annual payment under biweekly: (M / 2) × 26 = M × 13 So biweekly pays the equivalent of one extra full monthly payment per year (13 vs 12). Effective extra principal per month: Extra = M / 12 This is what to pay each month if you cannot enroll in a biweekly program — paying 1/12 of M as additional principal accomplishes the same payoff acceleration. Example: $300,000 loan at 6.5% over 30 years Monthly payment: $1,896 Standard total interest paid: ≈ $382,500 Total payments: 360 over 30 years. Biweekly half-payment: $948 every 2 weeks Total interest paid: ≈ $304,900 Loan retires in: ≈ 25 years 4 months (4.7 years faster) Interest saved: $77,600 — roughly 26% lower lifetime interest.

How to use this calculator

Enter your loan amount (current balance for an existing loan, or original loan amount for a new purchase analysis).
Enter your annual interest rate — the note rate on the mortgage, not the APR.
Enter the loan term in years. The biweekly benefit is largest on longer loans (30-year saves more years than 15-year).
Compare standard monthly vs biweekly results. Look at total interest paid, time to payoff, and years saved.
Decide on implementation. Three equivalent approaches: (1) enroll in your lender's biweekly program (watch for setup fees), (2) make one extra full monthly payment per year (often called the "13th payment"), or (3) pay 1/12 of the monthly payment as extra principal each month (the simplest if you have autopay).
If your lender charges a setup fee, run the same calculation on a "monthly + 1/12 extra principal" schedule — the savings are identical without the fee.
Confirm that extra payments are applied to principal, not held as future-month prepaid interest. Some lenders default to the wrong application — write "apply to principal" on the check or use the lender's online "principal-only" option.

Worked examples

Classic 30-year mortgage — meaningful savings

$300,000 loan at 6.5% over 30 years Monthly schedule: Monthly payment: $1,896 Total interest paid: $382,500 Loan retired: 360 months (30 years) Biweekly equivalent: Half-payment: $948 every 2 weeks Total interest paid: ≈ $304,900 Loan retired: ≈ 304 months (25 years, 4 months) Savings: $77,600 in interest, 4 years 8 months earlier payoff.

Already 5 years into a 30-year mortgage

Original loan: $400,000 at 6.0%, currently 5 years in Current balance: ≈ $375,000 Remaining term: 25 years (300 months) Switching to biweekly now (or adding 1/12 of payment as extra principal): Standard remaining interest: ≈ $307,000 Biweekly remaining interest: ≈ $244,000 Savings: $63,000, and the loan is paid off about 4 years earlier. Even starting late, the math still works heavily in your favor.

Same effect, no lender enrollment

$250,000 loan at 7.0% over 30 years, monthly payment $1,663 Lender charges $300 to enroll in biweekly autopay. Alternative: add $138.58 (1/12 of $1,663) as extra principal each month manually. Result: identical payoff timeline and identical interest savings — without the $300 fee. Setup: when you autopay your monthly mortgage, also schedule a $138.58 "principal-only" payment for the same date. Most lenders have this option in their online portal.

When to use this calculator

Use this calculator when you already own a home with a mortgage and want to evaluate whether accelerated payoff makes sense, or before you sign a mortgage if you want to see what an extra payment per year actually buys. The biweekly approach is the most popular flavor of "pay off the mortgage early" precisely because it requires minimal behavior change — money comes out of the same paycheck cycle that pays everything else.

The biweekly approach is best for people who: are paid biweekly and find it psychologically easier to align mortgage payments with paychecks, want to retire the mortgage before retirement, or have a stable cash-flow surplus and no higher-priority use for the extra ~$130–$200/month.

Skip biweekly (or any accelerated mortgage payoff) when: your mortgage rate is lower than expected investment returns (a 3.0% mortgage from 2020 vs. 7% expected equity returns favors investing instead), you don't have an emergency fund built, you carry credit card or other high-interest debt, or you have not yet maxed your retirement accounts and employer match. The opportunity cost matters.

Pair this with the mortgage-payment calculator (to confirm your monthly base payment) and the mortgage-refinance calculator (because refinancing to a lower rate and then making biweekly payments often dominates either move alone).

Common mistakes to avoid

Paying a setup fee to a "biweekly program" without checking that you can't do it free yourself. Most lenders allow voluntary principal-only payments via their online portal — same result, no fee.
Confusing "bi-weekly" with "twice a month." Bi-weekly is every two weeks (26 payments/year). Twice a month (semi-monthly) is 24 payments/year — same as monthly with no acceleration.
Making extra payments without checking how the lender applies them. Some servicers credit extra dollars toward future months' payments by default (which provides zero benefit). Always specify "apply to principal."
Accelerating a low-rate mortgage instead of investing. A 3% mortgage and a 7% expected equity return means each extra dollar paid to the mortgage gives up about 4% per year in expected return. The math reverses at higher mortgage rates.
Forgetting that biweekly is just monthly + 1/12 extra. Many people see "biweekly" as magic; it is not — it is the same as adding one full extra payment per year. Recognizing this opens up flexibility (you can do it without enrolling, you can do more than 1/12, you can pause when cash is tight).
Locking into a biweekly autodraft without keeping a buffer. A 26-pay schedule means months with three deductions (twice per year). If your checking account can't handle that month's rhythm, you'll overdraft. Keep an extra cushion or stay with monthly + voluntary extra.

Frequently Asked Questions

Sources & further reading

Should I pay extra on my mortgage? — U.S. Consumer Financial Protection Bureau
Making extra payments — what to know about prepayment — U.S. Consumer Financial Protection Bureau
Mortgage prepayment and acceleration — guidance — U.S. Department of Housing and Urban Development

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