Debt Payoff Calculator

How the debt payoff calculator works

Each month, your lender adds interest (balance × APR ÷ 12), then subtracts your payment. The calculator loops that until the balance hits zero, counting months and total interest as it goes.

Flip it around: hand it a target month count and it runs the amortization formula backwards to find the required payment. Both directions use the same math your lender uses. No black box.

Formula

Where B is the balance, r the monthly rate (APR ÷ 12), and P the monthly payment.

Example

$10,000 at 18% APR, paying $300 a month. Monthly interest starts at $150. Half of every payment feeds the lender.

Result: 47 months to debt-free, $4,100 in total interest.

Want it gone in 24 months instead? That takes about $499 a month. The $199-a-month difference buys nearly two extra years of freedom and saves roughly $2,100 in interest. Hard to find a clearer picture of what extra payments are worth.

Why minimum payments are a trap

Card minimums usually run 1–2% of the balance. On that same $10,000 at 18%, a $200 minimum stretches past 7 years and costs over $7,100 in interest. You'd pay 70% extra for the privilege of going slow.

Minimums aren't designed for your freedom. They're designed for the lender's interest income. Which is why the highest-ROI move in most people's finances is painfully boring: pay more than the minimum on high-APR debt. It's a guaranteed, tax-free 18–25% "return." Nothing in the market offers that.

Where your payment actually goes (amortization)

Early on, your payment mostly feeds interest. Late in the loan, it mostly kills principal. Same $300, totally different split.

On the $10,000 / 18% / $300 example: month 1 sends $150 to interest and $150 to principal. By month 40, that same $300 sends about $30 to interest and $270 to principal.

That's why extra payments early punch so far above their weight. Every early dollar wipes out its own future interest, compounding in your favor for all the months that remain. The chart above shows it: watch the balance curve steepen as it falls.

The true cost of "affordable" monthly payments

Lenders advertise the monthly payment. Never the total cost. The total is horrifying, which is exactly why.

A $25,000 car loan at 9% stretched over 84 months: "only $398 a month!" Total interest: about $8,400. The same loan over 48 months at $620 a month: about $4,700 in interest. You'd "save" $222 a month but hand over $3,700 extra and stay in debt three years longer.

Before signing anything, run both scenarios in the calculator above. The monthly payment is marketing. The total interest is the price.

Three ways to accelerate payoff

• Raise the payment. Try +$50 and +$100 in the calculator. The interest savings are usually shocking.
• Cut the rate. A 0% intro-APR balance transfer or a cheaper personal loan can halve your interest cost overnight.
• Attack in the right order. Juggling several debts? Our Snowball vs Avalanche calculator picks the payoff order that fits you.

Frequently asked questions

What happens if my payment only covers the interest?

The balance never moves. You're on a treadmill, and the calculator will tell you so. To make progress, each month's payment has to beat balance × APR ÷ 12.

Should I pay off debt or invest instead?

Compare the rates. Wiping out 20% credit card debt is a guaranteed 20% return, and no investment reliably beats that. Under about 7%, investing while paying normally is defensible. Between the two, it's judgment call territory.

Does the calculator handle extra one-time payments?

Approximate them: bump the monthly payment for a few months, or subtract the lump sum from the balance and re-run. On the example above, a $1,000 lump sum saves roughly 4 months and $600-plus in interest.

Why does the payoff date differ slightly from my statement?

Most cards compound interest daily; this calculator compounds monthly. The gap is a few dollars. Fees, penalty APRs, and new charges move real-world dates more.

Is it better to pay a little extra or save an emergency fund first?

Sequence it: stash a $1,000 starter emergency fund first, so the next surprise doesn't land back on the card. Then attack the debt hard. Then build the fund to 3–6 months of expenses.

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