About the Loan Comparison Engine
The Loan Comparison Engine puts up to 4 loan scenarios head-to-head and shows monthly payment, total interest, total cost, and effective APR (APR including origination fees, which is the apples-to-apples number for comparison — raw interest rates with different fee structures lie). Supports auto, personal, mortgage, and student loans; toggles between fixed and adjustable-rate; overlays amortization curves so you can see which loan actually pays down fastest.
It is built for refi shoppers comparing three lender quotes, car buyers stuck between manufacturer 0% APR + no rebate and standard rate + $3K rebate, mortgage applicants comparing 15-year vs 30-year vs 20-year, debt consolidators weighing personal-loan offers, and anyone whose three lender quotes have different rates, different fees, and different terms (which makes them basically incomparable until you compute effective APR).
All comparison math runs locally in JavaScript. Loan principal, rate, term, and fee inputs never leave your device. The page makes no network call after first load. Loan-shopping data is sensitive (and often resold by aggregator sites to outbound sales pipelines); this calculator never sees it.
Two practical rules: compare effective APR, not headline rate — a 6.5% rate with $5K origination on a $200K loan effectively costs more than a 6.875% rate with no points; the calculator surfaces this. And discount points only pay off if you keep the loan past the break-even period — divide point cost by monthly savings to get the break-even month count; refinancing or selling before that point loses money on points. For ARMs, always check the worst-case payment after the fixed period; the start rate is the bait, the rate caps are the hook.
Expandable month-by-month schedule for each loan showing payment breakdown and remaining balance.
| Month | Payment | Principal | Interest | Balance |
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Find exactly when one loan becomes cheaper than another. Compare total cost month by month.
See how extra monthly or one-time lump-sum payments reduce your loan cost and payoff time.
How to Use the Loan Comparison Engine
Start by entering the details for at least two loans you are considering. For each loan, provide the principal amount (how much you are borrowing), the annual interest rate, the loan term in months or years, and any origination fees the lender charges upfront. You can also toggle between Fixed and ARM (adjustable-rate mortgage) types to model different scenarios. The tool instantly calculates monthly payments, total interest, total cost, and effective APR for each loan and displays a side-by-side comparison table. The best value in each metric is highlighted in green, and the overall winner is announced at the top so you can identify the cheapest option at a glance.
Understanding the Amortization Chart
The amortization overlay chart plots the remaining balance of each loan over time on a single graph. Lines start at the full principal and curve down to zero as the loan is paid off. Shorter terms produce steeper curves because more of each payment goes toward principal. Where two lines cross is a visual indicator of the break-even point: before the crossing, one loan has a lower remaining balance; after it, the other loan catches up and overtakes. This chart is especially useful when comparing a shorter-term loan with higher payments against a longer-term loan with lower payments. You can see at exactly which month the shorter loan has saved you more money in absolute terms.
Effective APR vs. Stated Interest Rate
The interest rate a lender quotes is not always the true cost of borrowing. Origination fees, discount points, and closing costs reduce the actual amount of money you receive, while the repayment schedule stays the same. The effective APR accounts for these fees by calculating what interest rate would produce the same monthly payment on the net amount you actually receive (principal minus fees). A loan advertised at 5.0% with a $2,000 origination fee might have an effective APR of 5.35%, making it more expensive than a 5.25% loan with no fees. Always compare effective APR, not the headline rate, when shopping for loans.
Fixed Rate vs. Adjustable Rate Loans
A fixed-rate loan locks your interest rate for the entire term. Your payment never changes, making budgeting predictable. An adjustable-rate mortgage (ARM) starts with a lower introductory rate that resets after a fixed period, typically 3, 5, 7, or 10 years. After the initial period, the rate adjusts annually based on a benchmark index plus a margin, subject to a periodic and lifetime cap. ARMs are attractive when you plan to sell or refinance before the adjustment period, but they carry risk if rates rise. This tool models ARM loans at their initial rate and notes the rate cap so you can evaluate worst-case scenarios. For a true apples-to-apples comparison, enter the ARM rate cap as a separate fixed-rate loan to see the maximum possible cost.
Break-Even Analysis for Loan Switching
Refinancing or switching lenders often involves upfront costs such as application fees, appraisal fees, and closing costs. The break-even analysis calculates at which month the cumulative savings from a lower payment outweigh the upfront costs of switching. If the break-even month falls within the time you plan to hold the loan, switching is financially worthwhile. If it falls after your expected holding period, the higher upfront costs never pay for themselves. Subscribers can use the built-in break-even tool to compare any two of the four loaded loans and see the exact month and dollar savings. This is critical for refinancing decisions on mortgages and auto loans.
How Extra Payments Accelerate Payoff
Making additional payments beyond the required minimum is one of the most powerful ways to reduce the cost of a loan. Extra payments go directly toward the principal, which reduces the balance that accrues interest in future months. On a $250,000 mortgage at 6.5% over 30 years, adding just $200 per month to your payment saves over $95,000 in interest and cuts roughly 7 years off the loan. A one-time lump-sum payment, such as a tax refund or bonus, has a similar accelerating effect. The earlier the lump sum is applied, the greater the savings because it prevents interest from compounding on that portion of the balance for all remaining months. Subscribers can model both types of extra payments and see the exact time and money saved.
Tips for Getting the Best Loan
First, shop with at least three lenders. Rates and fees vary significantly even for the same borrower profile. Second, compare effective APR, not just the quoted rate, because fees hidden in origination charges can make a low-rate loan more expensive. Third, consider the total cost over your expected holding period rather than just the monthly payment. A 15-year mortgage has higher monthly payments than a 30-year mortgage but saves tens of thousands in interest. Fourth, watch for prepayment penalties that could limit your ability to make extra payments or refinance early. Fifth, if you are comparing an ARM against a fixed-rate loan, model the worst-case scenario by entering the ARM cap as a fixed rate to see your maximum exposure. Use this tool to run all those scenarios in minutes instead of hours.
Looking for related tools? Try our Compound Interest Calculator to see how your savings grow, or our Debt Payoff Planner to build a strategy for eliminating existing debt. Explore all Everyday Calculator tools.
Frequently Asked Questions
What is the difference between interest rate and APR?
The interest rate is the raw cost of borrowing. APR (annual percentage rate) includes the interest rate plus upfront fees like origination and points, expressed as a yearly rate. APR is the better apples-to-apples number when comparing offers, which is why this tool highlights effective APR.
Is a shorter loan term always better?
A shorter term saves a lot of interest and builds equity faster, but the monthly payment is higher. On a $300,000 mortgage at 7%, a 15-year term pays roughly $185,000 less interest than a 30-year term but costs about $700 more per month. The right answer depends on your cash flow.
How much does a small rate difference really matter?
More than most people expect. On a 30-year $300,000 mortgage, the gap between 6.5% and 7.0% is roughly $100 a month, or about $36,000 over the life of the loan. On large, long loans, even a quarter point matters.
When does an ARM make sense?
An adjustable-rate mortgage can make sense if you plan to sell or refinance before the fixed period ends (typically 5, 7, or 10 years) and the starting rate is meaningfully lower than the fixed-rate alternative. Review the rate caps carefully so you know the worst-case payment.
Should I pay points to buy down my rate?
Each discount point typically costs 1% of the loan amount and lowers the rate by about 0.25%. To decide, calculate the break-even: divide the points cost by the monthly savings to see how many months until you recover the cost. If you'll keep the loan longer than that, points pay off.