Calculate monthly payments, total interest, and full amortization for personal loans, auto loans, student loans, and SBA business loans. 2026 US rates included.
How Loan Payments Are Calculated
Every fixed-rate loan — personal, auto, student, or business — uses the same amortization formula. Each payment is identical, but the split between interest and principal shifts every month.
M = P × [r(1+r)^n] / [(1+r)^n − 1]
In plain terms: early payments are mostly interest. Later payments are mostly principal. This is why paying a little extra in the first 12–18 months of a loan saves disproportionately more than extra payments near the end.
2026 US lending rate landscape
Loan type
Credit score
Typical APR range
Personal (excellent credit)
760+
7%–11%
Personal (good credit)
680–759
11%–19%
Auto loan — new vehicle
720+
5.5%–8%
Auto loan — used vehicle
680+
8%–12%
Federal student loans (2024–25)
N/A
6.53%–9.08%
SBA 7(a) business loan
680+
10%–13%
Credit card (carry a balance)
Any
20%–29%
The loan term trade-off no one talks about
Longer term = lower payment, much higher total cost. $25,000 at 9% APR: 36 months = $795/month, $3,600 total interest. 60 months = $519/month, $6,100 total interest. The 5-year loan saves $276/month but costs $2,500 more over time. Your cash flow situation decides which makes sense — but go in knowing the real cost.
When to use a 0% APR credit card instead
For amounts under $10,000 that you can pay off in 12–18 months, a 0% intro APR credit card (Chase Freedom Flex, Citi Double Cash, etc.) often beats even the best personal loan rate. You pay no interest during the promotional period. Just make sure you can pay it off before the rate resets — typically to 19%–29%.
Frequently Asked Questions
With a FICO score of 720–759, you're looking at roughly 10%–14% APR from most online lenders in 2026 — think SoFi, LightStream, or Marcus. With a 760+ score you can often get under 10%, sometimes as low as 7%–8% through credit unions. The spread between excellent and good credit is about 3–5 percentage points, which on a $20,000 loan over 5 years is the difference between $383/month and $416/month — roughly $2,000 total over the life of the loan.
At current new car loan rates (roughly 6%–8% for well-qualified buyers), a $30,000 60-month auto loan runs about $580–$608/month. A 72-month term drops it to $487–$516/month but costs you an extra $700–$900 in total interest. Used car loans typically run 1–3% higher than new car rates through dealerships — credit unions and banks often beat dealer financing, so always get a pre-approval before walking into a dealer.
The interest rate is the base borrowing cost. APR adds in all the fees — origination fee (typically 1%–8% of the loan), prepayment penalties if any, and other charges — expressed as a yearly rate. On a $15,000 loan with a 5% origination fee and a 9.99% interest rate, your APR comes out around 14%–15%. This is why LightStream (no origination fee) often beats a competitor with a lower advertised rate but a hefty origination fee. Always compare APRs. For auto loan analysis with term comparison, use our [Auto Loan Calculator](/calculators/auto-loan-calculator/).
Refinancing federal student loans is a permanent decision — you lose income-driven repayment plans, PSLF eligibility, and federal forbearance options. If you work in the public sector or might need payment flexibility, don't refinance federal loans. If you have a stable income, no plans for PSLF, and federal rates above what you'd qualify for privately (roughly 5.5%–8.05% for 2024–25 federal loans), refinancing into a private loan at 5%–6% could save thousands. Run the numbers for your specific balance and remaining term.
Easiest method: pay bi-weekly instead of monthly. You make 26 half-payments per year instead of 12 full payments — that's one extra full payment annually with zero budgeting drama. On a 5-year $20,000 loan at 12% APR, bi-weekly payments knock about 5 months off and save roughly $600 in interest. Before you do this, confirm your lender applies extra payments to principal immediately and doesn't charge prepayment penalties — most modern lenders don't, but worth a quick call.
SBA 7(a) loans — the most common type for small businesses — typically require a personal FICO of 650+ though most lenders prefer 680+. The SBA itself doesn't set a minimum, but approved lenders do. Beyond credit score, you'll need 2+ years in business, $100,000+ in annual revenue, and no recent bankruptcies or defaults on government loans. Rates on SBA 7(a) loans in 2026 run prime + 2.25%–4.75%, putting most borrowers in the 10%–13% range.
