Interest & APR

Interest is simple, not compounding, and it's computed once — from the full duration and aprBps fixed at listing creation — regardless of when repayment actually happens. Repaying on day 1 of a 90-day term still owes the full 90 days of interest; there's no accrual-based discount for repaying early.

The formula

uint256 constant BPS = 10_000;
uint256 constant YEAR = 365 days;

function interestOwed(uint256 loanAmount, uint16 aprBps, uint32 duration) returns (uint256) {
  if (loanAmount == 0 || aprBps == 0 || duration == 0) return 0;
  return (loanAmount * aprBps * duration) / (BPS * YEAR);
}

In plain terms: interest = loanAmount × (aprBps ÷ 10,000) × (duration ÷ 31,536,000 seconds). A year is always treated as exactly 365 days — there's no leap-year adjustment.

Worked example

At repay, the borrower owes loanAmount + interestOwed(id) — in this example, 1,006.575 USDG — transferred to the lender in a single call. There's no protocol cut taken from that transfer; the lender receives the full amount.