APR

Annual percentage rate (APR) refers to the yearly interest generated by a sum that's charged to borrowers or paid to lenders.

APR is based on borrow rate, which is calculated based on kink:

If the utilization is less than kink then the borrow rate is:

borrow_rate = base + base_multiplier * utilization

Otherwise, it's:

borrow_rate = base + base_multiplier * kink + multiplier * (utilization - kink)

Base, Base Multiplier, Multiplier and kink are the pool parameters that are set by the Admins and they can be changed if needed.

When we have the borrow rate it's used to calculate APR, with the passage of time:

borrow_apr = borrow_rate * (current_epoch - last_interaction_epoch) / (365 * 24 * 60 / 5)