Bank Loan Comparison Calculator and Costs

This bank loan comparison calculator estimates the monthly payment and total interest for one fixed-rate loan using its amount, APR and term. Enter the figures from a lender’s quote to see the payment estimate and interest cost; compare separate offers by running the calculation for each one.

Formula

The calculator uses the standard fixed-payment amortization formula. It converts the annual percentage rate (APR) to a monthly rate, calculates a level monthly payment, then subtracts the original principal from the sum of all scheduled payments to estimate total interest.

• P is the loan principal, in dollars.
• APR is the annual percentage rate entered as a percentage, not a decimal.
• r is the monthly rate: APR ÷ 1,200.
• n is the number of monthly payments: years × 12.
• M is the monthly payment, in dollars: P × r ÷ [1 − (1 + r)⁻ⁿ].
• Total interest is M × n − P, using the payment rounded to cents.

This model assumes a fixed rate and equal payments made monthly. A lender’s quoted APR and payment may reflect details this basic calculation does not include, so use matching figures when comparing estimates.

Worked Example

With the calculator’s defaults, the principal is $20,000, APR is 8%, and the term is 5 years.

1. Convert the term to months: 5 × 12 = 60 payments.
2. Convert APR to a monthly rate: 8 ÷ 1,200 = 0.0066667.
3. Apply the payment formula: $20,000 × 0.0066667 ÷ [1 − (1 + 0.0066667)⁻⁶⁰] ≈ $405.53 per month, rounded to the nearest cent.
4. Estimate total interest using the rounded payment: $405.53 × 60 − $20,000 = $4,331.80.

These are estimates from the stated assumptions, not a lender’s final payment schedule.

Assumptions

• The interest rate stays fixed for the full term.
• Payments are equal, made monthly, and begin according to a regular amortization schedule.
• Interest is modelled monthly at APR divided by 12.
• Fees, taxes, insurance, escrow, late charges and optional products are not included.
• The payment is rounded to cents before the total-interest calculation; a lender may adjust the final payment to clear a small remaining balance.

How to Compare Bank Loan Offers

A comparison is useful only when the figures describe the same borrowing need and the same costs. Record each offer’s amount, APR, term, payment schedule and any charges or conditions disclosed by the lender. Use this calculator for the same principal and term when isolating the effect of different APRs. If the term differs, the payment and total interest change together, so note both rather than treating the monthly payment as the whole comparison.

For example, extending a loan term generally spreads repayment over more months. That can lower the scheduled monthly payment while increasing the number of payments on which interest is charged. A shorter term can produce a higher scheduled payment but fewer payment periods. The calculator shows this basic trade-off for a fixed-rate loan; it does not establish which arrangement fits a person’s circumstances.

When comparing actual offers, check whether the amount being financed is identical. A quoted payment may include a different principal, financed fees or optional items. Also distinguish APR from a nominal interest rate: APR is intended to represent borrowing cost in a broader way, but the exact items included and how a particular offer is presented depend on its disclosure. Use the lender-provided APR and review the written terms rather than inferring missing details.

Costs and Details the Calculator Leaves Out

The output is not a complete cost-of-credit figure when a loan has costs beyond scheduled principal and interest. Origination or other charges, if applicable, may affect the cash received, amount financed or overall cost. A variable-rate loan can change its payment as its rate changes; this model cannot represent that path because it assumes the APR remains constant. Irregular payment dates, a balloon payment, interest-only periods, deferred payments or a non-monthly schedule also require a different calculation.

To make a practical comparison, read the lender’s full disclosure for the amount financed, payment amount and frequency, total scheduled payments, APR, fees and any rate-change provisions. Ask the lender to clarify a term you cannot reconcile. Do not add a fee to the principal in this calculator unless it is actually financed and you are intentionally modelling the larger balance; otherwise the resulting estimate will not match the quoted loan.

Common Comparison Mistakes

• Comparing monthly payments alone: A smaller payment can result from a longer term or a different principal, not necessarily a lower borrowing cost.
• Entering a decimal instead of a percentage: Enter 8 for an APR of 8%, not 0.08. The calculator divides the percentage by 1,200 to get a monthly rate.
• Mixing annual and monthly terms: The term field is in years. A five-year term is entered as 5, not 60.
• Ignoring fees or changing rates: The results cover the simplified fixed-rate schedule only.
• Overinterpreting rounded figures: The calculator displays cents, while actual payment schedules may differ slightly because of lender-specific rounding and timing.

A comparison calculator is a way to standardize arithmetic, not a substitute for reviewing contract terms. It does not predict approval, assess eligibility or determine whether a loan is appropriate. For an offer with unusual payment features, request its payment schedule and compare the disclosed cash flows directly.

Frequently Asked Questions

What does a bank loan comparison calculator show?
It estimates the monthly payment and total interest for a fixed-rate, fully amortizing loan from its principal, APR and term. It does not include unentered fees or other loan features.

How do I compare two bank loans?
Use the same principal and term to compare the payment and interest estimates, then review each lender’s APR and written disclosure for fees, payment timing and conditions. If terms differ, compare the full schedules as well as monthly payments.

Is APR the same as the interest rate?
Not necessarily. APR is a broader disclosed measure of borrowing cost than the nominal interest rate, though the components reflected can depend on the loan and applicable disclosure. Check the lender’s documents for what is included.

Why can a longer loan have more total interest?
A longer term usually means more scheduled payment periods. Even if the monthly payment is lower, interest can accrue over a longer repayment period; this calculator illustrates that effect under its fixed-rate assumptions.

Does the estimate include fees or insurance?
No. Fees, taxes, insurance, escrow and optional products are not inputs here. Review the lender’s disclosure for any amounts that apply to a particular offer.

This result is an estimate, and the lender’s disclosure gives the exact figures.

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2