Bi-weekly mortgage payment calculator
Borrow 300,000 at 6.5% over 30 years with 26 payments a year and each installment is 874.76, with 382,311.79 in interest over the life of the loan. The payment is sized so the stated term is the real term. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Principal amount
- 300,000
- Annual rate
- 6.5
- Term years
- 30
- Periods per year
- 26
- Payment count
- 780
- Biweekly rate
- 0.0025
- Biweekly payment
- 874.76
Paying a home loan every two weeks is a different cash-flow rhythm from a conventional monthly note, and the installment is not simply half of a monthly payment. Originators quote a principal, a nominal annual interest rate, and a term in years; this bi-weekly mortgage payment calculator turns those three figures into the fixed amount due every fourteen days so the mortgage still amortizes over the stated term with twenty-six compounding periods per year. It also returns the total interest paid if every bi-weekly installment is made on schedule through maturity. Zero-percent promotional rates are supported.
How the bi-weekly mortgage payment and total interest are computed
A bi-weekly mortgage in this calculator is a fully amortizing installment contract with twenty-six equal payments each calendar year, not twelve. When r is positive the standard annuity formula applies: bi-weekly payment equals principal times r times (1+r) to the n, divided by (1+r) to the n minus one. When the annual rate is exactly zero the payment collapses to principal divided by n, because there is no interest component to front-load.
After the closed-form payment is obtained, total paid is that economic payment times n, and total interest is total paid minus principal; currency fields are then rounded to cents so goldens stay stable across runtimes. This is a true bi-weekly amortizing loan: the payment is sized so the stated term is the actual term. It is not the popular accelerated trick of taking a monthly payment, dividing it by two, and sending that half-payment twenty-six times a year, which would retire the debt early and change lifetime interest.
Typical consumer terms are fifteen, twenty, and thirty years; the contract accepts any positive term up to fifty years so jumbo, reconstruction, and shorter notes still compute without a second tool. Principal must be greater than zero and the annual rate must be finite and non-negative.
What you can do with it
True bi-weekly origination worksheets
Turn amount financed, quoted APR, and a 15-, 20-, or 30-year term into the installment due every two weeks and the lifetime interest before the borrower signs.
FAQ
How is the bi-weekly mortgage payment calculated?
For a 0% APR, payment is principal/n. Total interest is n times the economic payment minus principal, then rounded to cents.
What happens if the term in years is not positive?
Zero, negatives, and missing values are rejected and are not billed.
Is this the same as paying half my monthly mortgage every two weeks?
No. That accelerated shortcut uses a monthly payment divided by two and typically pays the loan off early. This calculator sizes a true bi-weekly installment so the stated term is the actual term, with twenty-six compounding periods per year.
How many payments does a bi-weekly mortgage have?
Twenty-six a year, not twelve. A 30-year loan therefore has 780 installments and a 15-year loan has three hundred ninety, and the rate for each period is the annual rate divided by twenty-six.
What amount should I enter as the mortgage principal?
The amount borrowed after the down payment, not the price of the house: subtract cash down and other credits that reduce the loan, and add closing costs only if they are rolled into it.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/fin/bi-weekly-mortgage-payment \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"principal":300000,"annual_rate":6.5,"term_years":30}'const res = await fetch("https://api.kit.forhosting.com/fin/bi-weekly-mortgage-payment", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"principal": 300000,
"annual_rate": 6.5,
"term_years": 30
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/bi-weekly-mortgage-payment",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"principal": 300000,
"annual_rate": 6.5,
"term_years": 30
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/bi-weekly-mortgage-payment", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"principal":300000,"annual_rate":6.5,"term_years":30}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"principal":300000,"annual_rate":6.5,"term_years":30}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/bi-weekly-mortgage-payment", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"principal": 300000,
"annual_rate": 6.5,
"term_years": 30
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.bi_weekly_mortgage_payment",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
A term in years that is missing, zero, or negative is rejected with invalid_input and is not billed.
How the bi-weekly mortgage payment and total interest are computed
The periodic rate r is the quoted annual_rate divided by one hundred and then by twenty-six. The number of payments n is term_years times twenty-six; a thirty-year note therefore has seven hundred eighty installments, and a fifteen-year note has three hundred ninety.
Input contract, response shape, and error behaviour
Example: three hundred thousand financed at 6.5 percent for thirty years yields seven hundred eighty bi-weekly installments and a fixed payment a little under nine hundred dollars, with total interest taken from the closed-form schedule rather than from a monthly quote cut in half. POST a JSON body with three required fields. principal is the amount borrowed after down payment, not the contract price of the house: subtract cash down and other credits that reduce the note, then add financed closing costs only if they are rolled in. annual_rate is the nominal APR as a percent (six point five means 6.5 percent a year); aliases apr, rate, and interest_rate are accepted so origination forms can reuse their column names. term_years is the term in years; aliases term and years map to the same field. term_years must be a positive finite number no greater than fifty, and term_years times twenty-six must be a whole number of payments—zero, negatives, and missing values fail with invalid_input naming term_years, and those failures are not billed. Each numeric field may arrive as a JSON number or a numeric string; empty strings and non-finite values fail with a message that names the field. On success the body echoes principal, annual_rate, and term_years, reports periods_per_year (always twenty-six), payment_count, biweekly_rate, the rounded biweekly_payment, total_paid, and total_interest. Pair the JSON with your own year-by-year chart if you need every row; this endpoint returns the payment and the lifetime interest, not a seven-hundred-eighty-line table, so responses stay small for widgets and APIs.
Where a bi-weekly mortgage payment calculator earns its keep
Homebuyers use a bi-weekly mortgage payment calculator when a lender or credit union offers a true bi-weekly note and they need the amount that will leave their checking account every two weeks, plus the total interest they will pay if they stay for the full term. Originators drop the same three fields into worksheets so a fifteen-year bi-weekly quote can sit next to a thirty-year bi-weekly quote without mixing in a monthly payment that was never the product. Failed validation does not consume balance. Refinance shops re-run principal as the current payoff, annual_rate as the new offer, and term_years as the remaining or reset term, then read total_interest against the old note. Keep term_years positive, pin the rounded currency fields in tests, and you get reproducible bi-weekly mortgage figures for loan jackets, LMS plugins, and edge workers without standing up an amortization engine of your own.
Integration use cases
Fifteen-year versus thirty-year bi-weekly quotes
Hold principal and rate fixed, change only term_years, and compare biweekly_payment and total_interest without mixing in a monthly schedule.
Refinance and payoff checks on a bi-weekly note
Re-run the current payoff as principal with a new APR and term_years to see whether resetting a bi-weekly mortgage actually saves interest.
Technical questions
Does a 0% annual rate work?
Yes. Set annual_rate to 0. Bi-weekly payment is principal divided by the number of bi-weekly periods (term_years×26) and total interest is zero.
What does the bi-weekly mortgage payment calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.