About the Loan Comparison
Choosing between loan offers isn't always as simple as picking the lowest interest rate - different terms, fees, and payment structures can make a higher-rate loan actually cheaper overall. Our Loan Comparison Calculator lets you compare two loan offers side by side on equal footing.
How It Works
The calculator computes the full monthly payment, total interest, and total cost for two separate loan offers using the standard amortization formula, then shows both sets of results together so you can directly compare the real difference between the offers.
Formula & Methodology
Running the identical amortization formula twice - once per offer - and placing the results side by side is what makes an honest comparison possible, since rate and term interact in ways that aren't obvious from either number alone. A lower rate with a longer term can produce both a lower monthly payment and more total interest than a higher rate with a shorter term; only computing both offers fully and comparing total cost reveals which is actually true for any specific pair of offers.
Step-by-Step: Calculating It By Hand
- 1For each offer, convert the annual rate to a monthly rate and the term to months.
- 2Apply the standard amortization formula to each offer to find its monthly payment.
- 3Multiply each offer's monthly payment by its number of payments to find total cost, then subtract the loan amount to find total interest.
- 4Compare monthly payment and total cost side by side across both offers.
Examples
Rate versus term trade-off
A shorter-term loan at a slightly higher rate can end up costing less in total interest than a longer-term loan at a lower rate, once the extra months of interest are factored in.
Spotting the better deal
Two offers with similar monthly payments can have meaningfully different total costs once term length differs - this comparison makes that gap visible instead of hidden in the monthly number alone.
Advantages
- Compares two full loan offers side by side, not just the headline interest rate
- Shows monthly payment and total cost together for a complete comparison
- Works for any type of fixed-rate loan - personal, auto, or otherwise
- Removes the guesswork from comparing offers with different terms
Common Mistakes
- Choosing the loan with the lowest interest rate without checking total cost across the full term
- Not accounting for origination fees or other costs that aren't reflected in the interest rate alone
- Comparing offers with different terms purely on monthly payment, which can mask a much higher total cost
- Forgetting to verify both offers are for the exact same loan amount before comparing
Edge Cases to Watch For
- Origination fees and other closing costs aren't part of the base amortization formula and should be added to each offer's total cost separately for a fully accurate comparison.
- Offers with different loan amounts (not just different rates or terms) require normalizing before comparison, since a larger loan naturally costs more in absolute terms.
- A lower monthly payment doesn't necessarily mean a better deal - always check total cost across the full term, not just the payment figure.
- APR (which factors in fees) is a more complete single-number comparison than the interest rate alone, though this calculator focuses on payment and interest specifically.
Common Use Cases
- Comparing two loan offers before choosing a lender
- Evaluating rate-versus-term trade-offs across different offers
- Making sure a lower monthly payment isn't hiding a higher total cost
- General financial decision-making when multiple financing options are available