Secured Personal Loan Comparison Calculator

This calculator compares the estimated monthly payments and total interest for one secured personal loan using the amount, APR, and term you enter. It does not rank lenders or determine approval; enter each lender’s quoted figures separately to compare estimates on the same basis.

Formula

The estimated level monthly payment is calculated as:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount borrowed, in dollars.
• r is the monthly interest rate, calculated as APR ÷ 1,200. APR is entered as a percentage per year.
• n is the number of monthly payments, calculated as loan term in years × 12.

Estimated total interest is (monthly payment × n) − P. This calculator uses the unrounded payment formula for its displayed monthly payment, rounded to cents, and then uses that displayed payment to estimate total interest. Actual payment schedules can differ by cents because lenders may round each installment and handle the final payment separately.

Worked Example

Using the defaults: a $20,000 loan, 8% APR, and a five-year term.

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

Assumptions

• The APR and payment remain fixed throughout the term.
• Payments are level monthly installments, made at the end of each monthly period.
• Interest compounds monthly at APR divided by 12.
• The calculation excludes fees, taxes, insurance, and other charges; none are entered as calculator inputs.

What a Secured Personal Loan Comparison Shows

A secured personal loan is a loan backed by collateral: an asset the borrower pledges to secure repayment. The collateral may be subject to a claim under the loan agreement, and failure to meet the agreement’s requirements can put the asset at risk. The asset and the consequences of default depend on the lender’s contract and applicable rules; review those documents rather than assuming every secured loan works the same way.

This calculator compares payment arithmetic, not the full terms or safety of an offer. To compare two offers, enter each one’s principal, APR, and term in turn, keeping the assumptions consistent. For example, a $20,000 offer over five years can be compared with another $20,000 offer over the same five-year period. If the amounts or terms differ, the payment difference reflects those differences as well as the APR, so it cannot be attributed to interest alone.

A lower monthly payment does not by itself mean lower borrowing cost. A longer term often spreads repayment across more installments and can increase total interest, even when the monthly payment falls. Compare the total amount repaid and the contract terms alongside the monthly figure.

How to Compare Offers Carefully

• Use the same amount and term first. Holding these constant makes payment estimates easier to interpret.
• Use each lender’s written APR and payment schedule. Do not substitute an advertised or assumed rate. If fees affect the quoted APR, use the APR disclosed for that offer.
• Check what the APR includes. The calculator does not take fees as a separate input, and its formula cannot reproduce a lender’s fee treatment or itemized closing costs.
• Read collateral and default provisions. Identify what asset secures the debt, how it is valued, and what the agreement says can happen after missed payments.
• Check early-payment and late-payment terms. These can affect the actual cost or timeline but are not modelled here.
• Compare the lender’s disclosed total repayment figure. Differences from this estimate may reflect fees, rounding, payment dates, or contract-specific calculations.

When offers have different loan amounts, terms, or included charges, first make clear which differences you are comparing. A calculator result is an estimate based on the inputs, not a complete offer comparison.

Costs and Limits of the Estimate

The result assumes a fixed APR and a regular monthly schedule. It does not calculate variable-rate changes, irregular first or final payment periods, skipped payments, extra principal payments, late charges, or an origination fee. If a lender provides a payment schedule or a total repayment amount, use that document for the offer’s exact figures.

The input limits are calculator boundaries, not statements about the amounts, rates, or terms lenders offer. Obtain the actual APR, term, fees, collateral details, and payment amount from the lender’s disclosure. Even a small difference in APR or payment rounding can change the total over many months.

A secured loan is not automatically cheaper or safer than an unsecured loan. The comparison depends on the offer and the consequences of pledging collateral, which the payment formula cannot measure. The calculator does not assess eligibility, affordability, or whether a particular loan fits someone’s circumstances.

Frequently Asked Questions

What is a secured personal loan?
A personal loan backed by collateral. The agreement identifies the collateral and explains the terms; missed obligations can put the pledged asset at risk.

How do I compare secured personal loan offers?
Compare written APRs, loan amounts, terms, payment schedules, fees, collateral requirements, and default provisions. Use this calculator for a consistent payment and interest estimate, then check it against each lender’s disclosure.

Does a lower monthly payment mean I pay less overall?
No. A longer term can reduce the monthly payment while increasing the total interest paid. Compare both the monthly estimate and total repayment figures.

Does this calculator include fees?
No. It uses the entered principal, APR, and term only. It does not separately add origination or other fees, so the result may not match a lender’s full repayment disclosure.

Can I use it to compare secured and unsecured loans?
You can compare their payment arithmetic if you enter each offer’s figures, but the calculator does not account for collateral risk, contract differences, or other non-payment terms.

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

Related

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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