Personal Loan Calculator with APR & Amortization
Enter your loan amount, annual interest rate, repayment term, and origination fee percentage. The calculator derives your exact monthly payment using the standard amortization formula, builds the full month-by-month repayment schedule, and — when an origination fee is present — computes the fee-inclusive effective APR so you can compare competing loan offers on a like-for-like basis.
Monthly payment
$322.67
36 payments · 10% nominal APR
Total interest
$1,616.19
Total paid
$11,616.19
Effective APR
Effective APR
10.00%
Balance over time
Full amortization schedule (36 months)
| Mo. | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | $322.67 | $83.33 | $239.34 | $9,760.66 |
| 2 | $322.67 | $81.34 | $241.33 | $9,519.33 |
| 3 | $322.67 | $79.33 | $243.34 | $9,275.98 |
| 4 | $322.67 | $77.30 | $245.37 | $9,030.61 |
| 5 | $322.68 | $75.26 | $247.42 | $8,783.20 |
| 6 | $322.67 | $73.19 | $249.48 | $8,533.72 |
| 7 | $322.67 | $71.11 | $251.56 | $8,282.16 |
| 8 | $322.67 | $69.02 | $253.65 | $8,028.51 |
| 9 | $322.67 | $66.90 | $255.77 | $7,772.74 |
| 10 | $322.67 | $64.77 | $257.90 | $7,514.84 |
| 11 | $322.67 | $62.62 | $260.05 | $7,254.79 |
| 12 | $322.68 | $60.46 | $262.22 | $6,992.58 |
| 13 | $322.67 | $58.27 | $264.40 | $6,728.17 |
| 14 | $322.67 | $56.07 | $266.60 | $6,461.57 |
| 15 | $322.68 | $53.85 | $268.83 | $6,192.75 |
| 16 | $322.68 | $51.61 | $271.07 | $5,921.68 |
| 17 | $322.67 | $49.35 | $273.32 | $5,648.36 |
| 18 | $322.67 | $47.07 | $275.60 | $5,372.75 |
| 19 | $322.67 | $44.77 | $277.90 | $5,094.85 |
| 20 | $322.67 | $42.46 | $280.21 | $4,814.64 |
| 21 | $322.67 | $40.12 | $282.55 | $4,532.09 |
| 22 | $322.67 | $37.77 | $284.90 | $4,247.19 |
| 23 | $322.67 | $35.39 | $287.28 | $3,959.91 |
| 24 | $322.67 | $33.00 | $289.67 | $3,670.23 |
| 25 | $322.68 | $30.59 | $292.09 | $3,378.15 |
| 26 | $322.67 | $28.15 | $294.52 | $3,083.63 |
| 27 | $322.67 | $25.70 | $296.97 | $2,786.65 |
| 28 | $322.67 | $23.22 | $299.45 | $2,487.20 |
| 29 | $322.68 | $20.73 | $301.95 | $2,185.26 |
| 30 | $322.67 | $18.21 | $304.46 | $1,880.80 |
| 31 | $322.67 | $15.67 | $307.00 | $1,573.80 |
| 32 | $322.67 | $13.11 | $309.56 | $1,264.24 |
| 33 | $322.68 | $10.54 | $312.14 | $952.10 |
| 34 | $322.67 | $7.93 | $314.74 | $637.37 |
| 35 | $322.67 | $5.31 | $317.36 | $320.01 |
| 36 | $322.68 | $2.67 | $320.01 | $0.00 |
How it works
The monthly payment is calculated with the standard amortization formula: PMT = P × r / (1 − (1 + r)^−n), where P is the principal, r is the monthly rate (annual rate ÷ 12), and n is the term in months. From that fixed payment, each month's interest portion equals the remaining balance multiplied by the monthly rate; the rest reduces principal. Because the balance shrinks every month, interest falls and principal rises — meaning early payments are mostly interest while later ones are mostly principal repayment.
The effective APR is the annualised internal rate of return (IRR) of the actual cash flows: you receive (principal − origination fee) at the start and pay back the fixed monthly instalment for n months. This rate is found by binary search over the equation netProceeds = PMT × (1 − (1 + r)^−n) / r, then multiplied by 12. When no origination fee is charged the effective APR equals the stated nominal APR; any fee pushes the effective APR higher because you borrow less but repay the same amount. This is the same calculation that underlies the US Truth-in-Lending (TILA) APR disclosure.
The full month-by-month schedule is built by accumulating the unrounded floating-point balance across all periods; only the values written to each row are rounded to 2 decimal places. This avoids rounding drift and ensures the final balance reaches exactly $0.00. The schedule is the primary output of the API endpoint and is suitable for embedding live repayment tables in fintech applications, affordability tools, and loan-comparison dashboards.
Frequently asked questions
What counts as an origination fee for APR purposes?+
An origination fee is a one-time upfront charge — expressed here as a percentage of the principal — that the lender deducts from the disbursed amount. Common examples include processing fees, underwriting fees, and administrative fees charged at closing. Prepaid interest, late-payment penalties, and optional add-ons (such as payment-protection insurance) are not origination fees and are not reflected in this calculator. If your lender quotes a flat dollar fee, divide it by the loan amount to find the equivalent percentage.
Why might my lender's APR differ from the effective APR shown here?+
Lenders must disclose APR under the US Truth-in-Lending Act but may include or exclude different fee categories depending on how the loan is structured. Some lenders compute APR using daily compounding (actual/365) rather than the monthly actuarial method used here, which can shift the figure by a fraction of a percent. This calculator is an educational tool only — always verify the APR figure in your official loan agreement (Loan Estimate or note disclosure). Nothing here constitutes financial or legal advice.
Is the API available for this calculator?+
Yes. POST to /api/v1/tools/personal-loan-calculator with a JSON body containing principal, annualRatePct, termMonths, and originationFeePct. The response includes the full monthly schedule — every row with payment, interest, principalPaid, and balance — plus summary figures for monthlyPayment, totalInterest, totalPaid, originationFee, nominalAprPct, and effectiveAprPct. This makes it straightforward to power loan-comparison widgets, affordability checkers, or repayment dashboards without doing the maths client-side.