Deferred payment loan calculator
Borrow 10,000 at 6% a year for 2 years and you owe 11,200 in one payment at maturity, 1,200 of it interest. Enter the amount, the yearly rate and the term in years to see what the deferral costs. Free in your browser.
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Worked example
- Principal amount
- 10,000
- Interest rate
- 6
- Term
- 2
- Interest amount
- 1,200
- Amount due
- 11,200
A deferred payment loan advances cash today and collects nothing until a stated maturity date, when the borrower owes a single lump-sum of principal plus simple interest. There is no monthly installment, no sinking-fund schedule, and no amortizing table: the entire obligation sits until term end. This deferred payment loan calculator takes principal, an annual simple-interest rate as a percent, and a positive term in years, applies the closed-form identity amount due equals P times one plus r times t, and returns the total amount due together with the interest component.
How a deferred payment loan builds the lump sum due at maturity
A deferred payment loan, sometimes called a single-payment loan or a balloon due at term, is the opposite of an amortizing installment contract. The lender advances a principal P today. The borrower makes no periodic payment during the life of the note.
Convert the annual percent into a decimal rate r equal to rate divided by one hundred. Let t be the term measured in years. Interest is then P times r times t, and the amount due is P plus that interest, which is the same as P times one plus r times t.
That identity is the business-math standard for interest-in-arrears notes: a ten-thousand principal at six percent for two years is ten thousand times one plus zero point zero six times two, which is eleven thousand two hundred, of which one thousand two hundred is interest. When the annual rate is exactly zero the product r times t vanishes and the amount due equals the principal, so an interest-free deferral does not invent a charge.
Term is measured in years, so a six-month deferral is term 0.5 and an eighteen-month note is term 1.5; the product r times t still has the dimension of a pure number. Money fields round to two decimal places so they match currency. This calculator does not compound intra-year, does not amortize, and does not apply a prepayment penalty: it prices hold-to-maturity simple interest on a loan that is silent until the due date.
Where a deferred payment loan calculator earns its keep
Household and small-business planners who already know the cash they need can post principal, rate, and term to fill a card with amount due and interest, then decide whether stretching the deferral is worth the extra interest. Educators teaching simple interest versus amortizing loans can seed classroom examples that fail loudly when term is not positive, instead of plotting a nonsense curve through a zero or negative year count. Failed validation does not consume balance.
Keep principal positive, term a positive number of years, and rate a percent, pin the rounded money fields in tests, and you get reproducible maturity balloons for widgets, LMS modules, and edge workers without a loan-origination stack of your own.
What you can do with it
Lender and broker rate pages
Turn a quoted annual simple rate and a chosen deferral into the lump sum a borrower will owe if they make no payment until maturity.
Compare deferral lengths on the same principal
Line up a one-year note against an eighteen-month note on the same cash advance and rank them by amount due, not by the headline rate alone.
Classroom simple-interest balloons
Show students that a deferred payment loan is I = Prt paid at the end, and reject zero or negative terms instead of inventing a due date.
FAQ
How is the lump sum due on a deferred payment loan calculated?
Send principal (>0), rate as an annual simple-interest percent (≥0), and term in years (>0). Money fields round to cents.
What happens if the term is zero, negative, or missing?
Term must be a finite number of years strictly greater than zero. Zero, negatives, booleans, empty strings, and non-numeric values are rejected and not billed.
Does this use compound interest or an amortizing monthly payment?
Neither. A deferred payment loan here is simple interest with no interim payments. The whole principal and the accrued interest are due together at maturity. For an amortizing business installment use a different tool.
How do I enter a six-month deferred payment loan?
Term is measured in years. A six-month deferral is term 0.5 and an eighteen-month note is term 1.5. Pair that term with the annual simple rate as a percent.
Does a deferred payment loan at 0% interest cost anything extra?
No. With a rate of exactly zero the interest is zero, so the amount due at maturity equals the money you borrowed and putting off payment without interest never adds a charge.
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/deferred-payment-loan \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"principal":10000,"rate":6,"term":2}'const res = await fetch("https://api.kit.forhosting.com/fin/deferred-payment-loan", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"principal": 10000,
"rate": 6,
"term": 2
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/deferred-payment-loan",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"principal": 10000,
"rate": 6,
"term": 2
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/deferred-payment-loan", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"principal":10000,"rate":6,"term":2}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"principal":10000,"rate":6,"term":2}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/deferred-payment-loan", 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": 10000,
"rate": 6,
"term": 2
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.deferred_payment_loan",
"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 that is not a positive number fails with invalid_input and is not billed.
How a deferred payment loan builds the lump sum due at maturity
On the maturity date the borrower pays one amount: principal plus the simple interest that accrued over the term.
Input contract, response shape, and error behaviour
Term is the field the product contract singles out: zero years, a negative deferral, or a non-numeric stand-in is never treated as a free gift or as a silent overnight loan. Example: principal ten thousand, rate six, term two yields interest one thousand two hundred and amount due eleven thousand two hundred. POST a JSON body with three required fields. principal is the amount advanced today as a finite number greater than zero (aliases amount and loan_amount). rate is the annual simple interest as a percent such as six for six percent per year, finite, at least zero, and at most one thousand (aliases annual_rate and interest_rate). term is the deferral in years as a finite number strictly greater than zero and at most one hundred; a six-month note is term 0.5 (aliases years and term_years). Each numeric field may arrive as a JSON number or as a numeric string. Missing fields, empty strings, booleans, non-finite values, a non-positive principal, a negative rate, and any term that is not positive fail with invalid_input naming the field and are not billed. On success the body echoes principal, rate, and term, and adds interest (P times r times t, rounded to cents), amount_due (the lump sum payable at maturity, rounded to cents), and a formula string restating the identity, the zero-rate collapse, and the units. This endpoint does not model compounding, origination fees, or early repayment; it computes the simple-interest balloon that is due if the borrower waits until maturity and pays in one transfer.
Where a deferred payment loan calculator earns its keep
Comparison tables that line up a one-year note against an eighteen-month note can call the same pure module from the browser for free previews and from the API when storing a scenario, guaranteeing that the balloon a visitor saw matches the balloon stored after they save a quote. Product teams building a balloon-note origination flow can request several terms with the same principal and rate and read amount_due on each option without writing their own multiply.
Technical questions
What does a deferred payment loan calculation cost on the API?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.