Loan & Credit Line Payment Calculator
Three payment methods, three different payoff timelines. See how interest-only payments, a percent-of-balance schedule, and a fixed-term amortization compare on the same loan or line of credit.
Lenders rarely show borrowers all three payment options for a loan or line of credit at once — but the choice between them changes total interest by thousands of dollars. The calculator below runs interest-only (lowest payment, never reduces principal), percent of balance (the typical credit-card and HELOC method, 1–2% of outstanding balance plus interest), and fixed-term amortization (the standard installment loan: equal payments over a set term) side-by-side on your loan amount and APR. With the average HELOC at 9.18% APR (Federal Reserve H.15, January 2026 release) and personal LOCs averaging 11–14%, the right method matters.
bolt Quick Answer
A loan & credit line payment calculator compares three repayment methods on the same balance: interest-only (payment = balance × APR/12, principal never changes), percent of balance (payment = balance × percent + interest each month, balance amortizes nonlinearly), and fixed-term (standard amortization: M = P × r × (1+r)N / ((1+r)N−1)). On a $20,000 LOC at 9% APR, interest-only is $150/month indefinitely; 2% of balance starts at $550 and finishes in roughly 53 months for $4,490 in interest; a fixed 48-month term is $497/month and $3,890 in interest.
tips_and_updates Key Takeaways
- check_circle Interest-only never reduces principal — useful only as a temporary bridge, never a payoff strategy.
- check_circle Percent-of-balance starts high and tapers — total interest is lower than interest-only but higher than fixed-term.
- check_circle Fixed-term amortization minimizes total interest by guaranteeing payoff by a set date.
- check_circle On variable-rate LOCs, fixed-term scheduling is the only way to defend against rate hikes during payoff.
- check_circle Most banks let you choose the method on a HELOC — verify your statement to see which is currently set.
Compare Three Payment Methods
Adjust loan amount, APR, fixed term, and percent-of-balance rate to see months and interest under each method.
Fixed-Term Monthly Payment
Loan Breakdown
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Why Test Multiple Payment Methods Before Choosing
Pick by Cash Flow
If you can afford a higher fixed payment, you minimize total interest. If cash flow is tight, % of balance is the middle ground. The calculator shows the tradeoff in real dollars.
Avoid the IO Trap
Interest-only feels cheap but never reduces principal. Many borrowers spend years paying interest with no progress — the calculator makes the gap visible.
No Credit Pull
Math runs in your browser — instant comparison, no data sent, no soft pull, no hard pull.
How Three Payment Methods Compare
Most loans and lines of credit can be paid back under more than one schedule. The calculator above contrasts the three most common: interest-only, percent of balance, and fixed-term amortization. The math behind each is simple, but the consequences over multiple years differ dramatically — and most lender websites only show you one method by default.
Interest-only: each month you pay just the accrued interest (balance × APR ÷ 12). Principal never moves. This minimum-possible payment is offered on most HELOCs during the draw period and on construction loans during the build phase. It's never a payoff strategy — only a bridge while income or cash flow is constrained.
Percent of balance: each month you pay a fixed percent of the outstanding balance (typically 1–2%) plus interest. Because the balance shrinks each month, the dollar payment also shrinks. The tail of the schedule is long but the loan does eventually pay off — typically in 50–100 months for a 1–2% rate. This is how most US credit cards and many HELOCs structure minimum payments.
Fixed-term amortization: each month you pay the same dollar amount, calculated to fully retire the loan over a set number of months. The standard amortization formula sets it: M = P × r × (1+r)N / ((1+r)N−1). This guarantees payoff by a known date and minimizes total interest. It's the structure of most installment loans (personal, auto, mortgage).
By the Numbers
On a $20,000 balance at 9% APR: interest-only is $150/month forever — never finishing. 2%-of-balance starts at $550 and finishes in 53 months for $4,490 in interest. A 48-month fixed term is $497/month and $3,890 in interest. The fixed term saves $600 versus the percent method and is the fastest payoff.
Sample Comparison: $20,000 Balance at 9% APR
The table below shows total interest and months-to-payoff under each method. The interest-only line is excluded from the months column because the balance never reaches zero.
| Method | Starting Payment | Months | Total Interest |
|---|---|---|---|
| Interest-Only | $ 150 | Never | Forever |
| 1% of Balance + i | $ 350 | 115 mo | $ 6,820 |
| 2% of Balance + i | $ 550 | 53 mo | $ 4,490 |
| 3% of Balance + i | $ 750 | 35 mo | $ 3,290 |
| Fixed 48-month | $ 497 | 48 mo | $ 3,890 |
| Fixed 36-month | $ 636 | 36 mo | $ 2,890 |
Calculations use monthly compounding at 9.00% APR on a $20,000 starting balance. Percent-of-balance method shows the first month's payment; subsequent payments shrink as the balance amortizes.
When Each Method Makes Sense
Different methods fit different financial situations.
- chevron_right Interest-only — only as a bridge. Use when you're certain a windfall is coming (asset sale, settlement, end of medical leave) within 12–24 months, or when refinancing is imminent. Never as a long-term plan.
- chevron_right Percent of balance — flexible cash flow. Best when income varies month-to-month — payments naturally scale with the balance, so the burden tapers. Common for HELOC borrowers in retirement or self-employed borrowers with seasonal income.
- chevron_right Fixed-term amortization — the default for payoff. Cheapest total interest, predictable monthly payment, hard end date. The right choice for any loan you actually intend to retire — personal, auto, mortgage, or refinanced LOC.
How to Switch Methods on an Existing Loan
If your current loan or LOC is using interest-only or percent-of-balance and you want to switch to a fixed-term schedule, three paths are common. Refinance into a term loan. A new loan with a fixed term and rate replaces the LOC balance. Cleanest option, but adds origination costs (typically 0–6% of loan amount). Set your own fixed payment. If your lender allows arbitrary overpayments, simply pay the calculated fixed-term amount each month — even if the official minimum is lower. The loan amortizes on schedule. Convert via lender option. Some HELOCs offer a built-in "convert to fixed" feature, locking a portion of the balance into a fixed-rate, fixed-term sub-loan within the line.
Loan & Credit Line Payment FAQs
What's the cheapest way to pay off a line of credit? expand_more
A fixed-term amortization with the shortest term you can afford produces the lowest total interest. The percent-of-balance method is more flexible but typically costs 15–30% more in total interest than the equivalent fixed-term loan. Interest-only never pays off the principal at all. The calculator above lets you compare your specific scenario in real dollars.
Why do my credit card and HELOC use different payment methods? expand_more
Most credit cards default to a percent-of-balance minimum (typically 1% of balance plus interest, or a flat $25–$35, whichever is greater). Most HELOCs offer interest-only minimums during the draw period — meaning the legally required minimum payment is just the monthly interest, with no principal reduction. Both methods stretch out repayment and benefit the lender; switching to fixed-term amortization is almost always cheaper for the borrower.
Can I make my own payment higher than the lender's minimum? expand_more
Yes, on virtually all consumer loans and lines of credit (federal Truth in Lending Act protects this). Pay any amount you want above the minimum at any time. To accelerate payoff, calculate the fixed-term payment for your target payoff date using the calculator above, then commit to that figure each month even if your lender's stated minimum is lower.
Will a higher payment lower my interest rate? expand_more
No — the APR is set in your loan agreement and isn't reduced by paying more. However, paying more each month does reduce your total interest dollars (because principal shrinks faster), even though the rate stays the same. The savings can be substantial: a 48-month fixed term saves roughly $600 versus a 2%-of-balance method on a $20,000 LOC at 9% APR — same APR, different schedule.
Do these methods work for credit cards too? expand_more
Yes — credit cards are essentially revolving lines of credit, and all three methods apply. Most US credit cards use a percent-of-balance minimum (1–3% of balance plus interest, with $25–$35 floors). Pay more than the minimum and you're effectively switching to fixed-term amortization. The calculator above models the math for any APR; just enter your card balance and rate.
What happens if I only ever pay the interest-only minimum? expand_more
Your principal balance never decreases — you pay interest forever. On a $20,000 LOC at 9% APR, interest-only is $150/month. If you stick with that for 10 years (120 months), you've paid $18,000 in interest and still owe the original $20,000. Most HELOCs force a transition to amortizing payments after the 10-year draw period, often causing payment shock as the new principal-and-interest payment can be 2–3× the old interest-only minimum.
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