Credit card payoff calculator
See when a card will be paid off at a fixed monthly payment and what the interest adds up to: a 5000 balance at 18% APR paid at 150 a month is clear in 47 months, with 1983.61 of interest. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Balance
- 5,000
- Apr
- 18
- Monthly payment
- 150
- Monthly rate
- 0.015
- First month interest
- 75
- Months
- 47
- Interest amount
- 1,983.61
Carrying a revolving credit card balance means every month a slice of the payment is eaten by interest before a dollar of principal moves. The two numbers people actually search for are how many months it will take to be debt-free at a fixed payment, and how much interest they will have paid by then. This credit card payoff calculator takes the current balance, the annual percentage rate, and the planned monthly payment, then walks a monthly compounding schedule until the card is clear. It returns months and total interest, plus the last installment which is often smaller than the regular payment.
What payoff months and total interest mean on a revolving card
A revolving credit card is not an installment loan with a known term. Interest is assessed each month on the remaining balance at the contractual monthly rate, which is the annual percentage rate divided by twelve, and only the leftover slice of the payment reduces principal. Payoff time is the number of those months until the balance reaches zero at a constant payment.
Total interest is the sum of every monthly interest charge along the way, not the headline APR, and not a simple-interest product of balance times rate times years, because the principal is falling. Early months are interest-heavy; later months are principal-heavy. If the payment is at or below the first month of interest, principal never moves: the card is the classic minimum-payment trap, and this calculator refuses to return an infinite or fabricated schedule.
The last installment is usually smaller than the regular payment because it only needs to clear leftover principal plus that month's interest. Households use months and interest together: months answers when they will be done, interest answers what the revolving balance actually cost.
Input contract, monthly walk, and error behaviour
Money inputs are rounded half-up to cents before the walk. Missing fields, empty strings, non-finite values, non-positive balance or payment, and a negative apr fail the same way and are not billed. Example: a five-thousand balance at eighteen percent APR with a one-hundred-fifty payment covers seventy-five of first-month interest and pays off in a finite number of months with a smaller final installment.
A walk that would exceed six hundred months is rejected so a payment that barely beats interest cannot run unbounded.
Where a credit card payoff calculator earns its keep
Households and budgeting apps use a credit card payoff calculator to turn a statement balance, a purchase APR, and a planned payment into two pinned numbers: months until the card is clear, and the interest that payment path will cost. Counselors and education pages run the same three fields at two or three payment sizes so a client can see how a larger payment shortens the calendar and cuts interest without building a custom amortization sheet. Failed validation does not consume balance.
Keep the payment strictly above first-month interest, pin the rounded months and interest in tests, and you get a reproducible revolving payoff for homework, counseling, and edge workers without standing up a card-core of your own. This tool does not apply new purchases, promotional 0% remaining-month clocks as a separate product, cash-advance APRs, or minimum-payment formulas from a cardholder agreement — only the snapshot walk from balance, APR, and a fixed monthly payment.
What you can do with it
Household payoff planning
Turn a statement balance, purchase APR, and planned monthly payment into months until the card is clear and the interest that path will cost.
Counseling and education pages
Reject a payment that does not cover monthly interest instead of drawing an infinite schedule, so clients see the minimum-payment trap as an error.
FAQ
How long will it take to pay off my credit card?
Enter the balance, the APR and the payment you plan to make each month. A 5000 balance at 18% with 150 a month takes 47 months and costs 1983.61 in interest, so 6983.61 in total.
Why is the last payment smaller than the others?
Because it only has to clear the principal that is left plus that month's interest. In the example of 5000 at 18% paid at 150 a month, the final installment is 83.61.
What if my payment doesn't cover the monthly interest?
Then the balance never falls, which is the classic minimum-payment trap. The calculator refuses to draw an endless schedule: your payment must be larger than the first month's interest, which is 75 on 5000 at 18%.
Why isn't the total interest just balance times rate times years?
Because the balance shrinks every month. Interest is charged on what is left, so early months are mostly interest and later months mostly principal; the total is the sum of every monthly 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/credit-card \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"balance":5000,"apr":18,"monthly_payment":150}'const res = await fetch("https://api.kit.forhosting.com/fin/credit-card", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"balance": 5000,
"apr": 18,
"monthly_payment": 150
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/credit-card",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"balance": 5000,
"apr": 18,
"monthly_payment": 150
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/credit-card", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"balance":5000,"apr":18,"monthly_payment":150}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"balance":5000,"apr":18,"monthly_payment":150}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/credit-card", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"balance": 5000,
"apr": 18,
"monthly_payment": 150
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.credit_card",
"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.
Limits
max_months | 600 |
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
If the payment does not cover the first month of interest the balance never falls, and the task fails with invalid_input instead of pretending an infinite schedule is a result.
What payoff months and total interest mean on a revolving card
This endpoint models a simple monthly compounding schedule with currency rounding to cents, not average-daily-balance, grace periods, late fees, or new purchases. It answers the worksheet question from a snapshot balance, APR, and planned payment so a budget can be compared against a larger payment without building a spreadsheet of hundreds of rows by hand.
Input contract, monthly walk, and error behaviour
POST a JSON body with three required finite numbers. balance is the current revolving amount and must be strictly greater than zero; aliases principal, amount, and card_balance map to the same field. apr is the nominal annual percentage rate as a percent, so eighteen means eighteen percent per year, not a decimal fraction, and must be greater than or equal to zero; aliases annual_rate, rate, and annual_percentage_rate. monthly_payment is the fixed amount applied each month and must be strictly greater than zero; aliases payment, monthly, and pmt. Each numeric field may arrive as a JSON number or a numeric string. The engine forms the monthly rate r as apr divided by one hundred divided by twelve, charges first-month interest equal to balance times r, and rejects the request with invalid_input naming monthly_payment when that payment does not cover monthly interest, because the balance would never fall. On success the body echoes the three inputs, reports monthly_rate and first_month_interest, then months until the card is clear, interest as the sum of monthly charges, total_paid, last_payment, and a short formula string.
Where a credit card payoff calculator earns its keep
Product teams and LMS plugins post balance, apr, and monthly_payment, then assert months and interest so a grader or onboarding flow never treats a payment that fails to cover monthly interest as a success.
Integration use cases
Compare payment sizes
Sweep monthly_payment across two or three budget levels to show how a larger payment shortens the calendar and cuts total interest.
Technical questions
How do I compute credit card payoff time and total interest?
Send balance, apr as a percent, and monthly_payment. The API walks a monthly schedule at r = APR/12 and returns months until the balance is zero plus interest as the sum of monthly charges.
What happens if my payment does not cover monthly interest?
The task fails with invalid_input. A payment at or below the first month of interest never reduces principal, so the calculator will not invent a payoff date and the request is not billed.
Does a zero APR still return months?
Yes. With apr of zero there is no monthly interest, months is the ceiling of balance divided by monthly_payment, interest is zero, and the last installment may be smaller than the regular payment.
Is the last payment always equal to monthly_payment?
No. The final installment is leftover principal plus that month's interest, which is usually smaller than the regular payment. total_paid is the sum of every installment including that last one.
What does the credit card payoff calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.