In a traditional IRA, you are required by law to begin taking withdrawals from your IRA in the year you reach age 73. The amount of the distribution is based on your age and the value of your account. Internal Revenue Service Publication 590 provides the information to calculate the required minimum distribution (RMD). The first RMD must start no later than April 1 of the year following the year in which you attain age 73. Failure to take the RMD results in an IRS penalty tax of 50% of the amount that should have been distributed.
You can find a RMD calculator through client portal. Click the User menu (head and shoulders icon in the top right corner) followed by Settings. Then under Account Settings find the Tax section and click RMD Calculator.