Loan comparison methodology

All four tools use one monthly fixed-rate model. It exposes fee treatment, initial net cash, a complete repayment schedule and the principal remaining on a common horizon.

Units and input scope

Amounts are non-negative USD values with at most two decimals. No currency conversion is performed. Annual interest is a plain percentage from 0% through 100%, with up to six decimal places. The term is one to 360 whole months; the comparison horizon is zero to 360. Initial net cash must be positive. Each entered fee belongs in exactly one category.

Initial principal and proceeds

Principal = base amount + financed fees. Net cash = base amount − withheld fees − upfront fees paid separately. Financed charges increase the debt; they do not increase usable cash. Upfront charges are treated as occurring at the same time as disbursement. Net cash is an economic time-zero amount, not necessarily the single deposit shown on a bank statement.

Payment and interest order

At positive monthly rate r, the level payment before cent rounding is principal × r / [1 − (1 + r)^(-term)]. At a zero rate it is principal divided by term. Each month’s interest is opening principal × annual rate / 12, rounded to cents with half cents rounded up. The regular amount caps at principal plus interest. Extra payments apply next and cap at the remaining amount owed.

In the final contractual month, the regular amount is adjusted to clear remaining principal plus interest. This handles a residual caused by cent rounding, including very small loan balances. Each row satisfies opening + interest − total paid = closing. Principal paid can be interpreted separately from interest. The schedule stops at zero balance.

Horizon and full-term cost

After horizon h, cost = payments through h + principal remaining after h − initial net cash. Horizon zero has no payments and retains the initial principal. After payoff, remaining principal stays zero and payments stay at the completed total. This is a nominal-dollar settlement comparison, without discounting, reinvestment returns, prepayment fees or daily accrued payoff interest.

Full financing cost = all modelled payments − initial net cash. In this model it also equals interest plus financed, withheld and upfront fees. Both costs can be displayed for each offer separately. The derived difference between offers is left unavailable when their initial net cash differs; unequal funding is explicitly flagged.

Cash-flow rate

The solver finds a monthly rate r for net cash = sum(payment at month m / (1 + r)^m). It uses the actual cent-rounded schedule, including extra payments and the adjusted final amount. Nominal annualized cash-flow rate is 12r. Effective annual rate is (1 + r)^12 − 1. Equal monthly periods are assumed, regardless of calendar-day counts.

These rates are model measures. The tool does not determine legally chargeable finance costs, regulatory APR treatment, odd-period adjustments or disclosure tolerances. A lender’s disclosed APR is not replaced by either annualized output.

Verification and privacy

Checks include independently calculated cent-rounded schedules, principal and cost identities, a zero rate, one-month and very small loans, fees in each category, extra payments, unequal proceeds, horizon zero and a horizon after payoff. Discount-root residuals are checked against initial net cash. Browser checks cover all tools, imports, downloads, mobile layouts and print reports.

Calculations run in the browser. There is no loan application, banking connector, account login, browser storage or lender submission. A saved JSON contains entered assumptions and a result snapshot; import recalculates the assumptions and ignores that old result as authority. Normal hosting can log page and asset requests.

Sources and definitions

The CFPB explains fees on personal instalment loans, why a monthly payment alone is insufficient for comparison and the distinction between interest and APR. These support the borrowing concepts. The specific monthly rounding, cash-flow rate calculation and invented examples are the original AllMarkets model, not a lender quote or a certified regulatory disclosure.