How to calculate the daily interest rate
You first take the Annual percentage rate (APR)* on your deposit and divide it by 365 to determine the amount of interest that accrues on a daily basis. Say you own 10,000 USDT tokens with 20% annual interest. You'd divide that rate by 365 (0.2 ÷ 365) to arrive at a daily interest rate of 0.0005479452055 which is approximately 5.5 USDT per day.
*An annual percentage rate (APR) is the yearly rate earned by an investment. APR shouldn't be confused with APY (annual percentage yield), a calculation that takes the compounding of interest into account.