Personal Loan Calculator

Origination fee deducted

originationFee = loanAmount × fee%

= $15,000 × 3%

= $450 deducted upfront — you receive $14,550

The lender deducts $450 before sending funds. You repay the full $15,000 in payments but only receive $14,550 — making the origination fee a hidden interest rate increase.

FTC Truth in Lending Act (TILA) — origination fee disclosure; Regulation Z

Effective APR (with origination fee)

Solve PMT × [(1+r)^n − 1] / (r×(1+r)^n) = netFunded for r, annualize

netFunded = $14,550, PMT = $494.64, n = 36

= NaN% effective APR (vs 11.50% stated)

Your effective APR is NaN% higher than the stated rate due to the origination fee. The fee is paid upfront but doesn't reduce the balance you're charged interest on — effectively raising your cost of borrowing. Always compare lenders using effective APR, not stated APR.

TILA-required APR calculation (Newton–Raphson IRR solve); Reg Z §1026.22

Monthly rate

r_month = APR / 12

= 11.5% / 12

= 0.9583%/month

The monthly rate is applied to the outstanding balance each month. Since the balance decreases with each payment, the dollar amount of interest charged also decreases over time — but the rate stays constant.

Monthly payment (PMT formula)

PMT = P × r / (1 − (1 + r)^−n)

P = $15,000, r = 0.9583%/mo, n = 36 mo

= $494.64/month

Each payment covers that month's interest charge with the remainder reducing principal. In month 1, most of the payment is interest; by the final month, nearly all is principal.

Time value of money annuity formula — standard loan amortization

Month 1 interest vs principal split

M1_interest = loanBalance × r_month

= $15,000 × 0.9583% = $143.75

= $143.75 interest · $350.89 principal (29.1% of first payment is interest)

29.1% of your first payment goes purely to interest — none of that reduces what you owe. This front-loading is why personal loans are expensive: early payments barely dent the balance.

Total paid and total interest

totalPaid = PMT × n · interest = totalPaid − loanAmount

= $494.64 × 36 − $15,000

= $17,807 paid · $2,807 interest (18.7% of principal)

You pay 18.7% of the loan in interest over 3 years. This is the cost of borrowing $15,000 at 11.5% APR.

True total cost (including origination fee)

trueCost = totalPaid + originationFeeAmount

= $17,807 + $450

= $18,257 all-in cost

Your total all-in cost is $18,257 — the $15,000 you borrow plus $2,807 in interest plus $450 in fees. You received $14,550 and paid $18,257 — a true cost of $3,707 above what you received.

Loan payoff midpoint

midpoint = month where cumulative principal repaid = 50% of loan

cumulative principal hits $7,500 at month 20

= Half the principal repaid by month 20 of 36

Due to front-loaded interest, you reach the halfway mark of principal repayment at month 20 — past 56% of the loan term. This is why refinancing or paying off early creates significant savings.

24-month payoff comparison

PMT_24 = loan × r / (1 − (1 + r)^−24)

= $15,000 × 0.9583% / (1 − (1 + 0.9583%)^−24)

= $702.60/mo · saves $945 in interest vs 36-month

Shortening to 24 months raises your payment by $207.96/mo but eliminates $945 in interest. If cash flow allows, shorter terms are always better on total cost — especially at high APRs like 11.5%.

Per-dollar cost of borrowing

cost per dollar = (totalPaid − loanAmount) / loanAmount

= $2,807 / $15,000

= $0.1871 in interest per $1 borrowed

For every dollar you borrow, you pay $0.1871 in interest cost. Use this to evaluate whether the loan purpose is worth the cost — a $15,000 loan at 11.5% over 36 months has a total interest cost of 18.7% of principal.