When you enter your W-2, TurboTax will calculate the credit.

You're eligible for the credit if you're:

• Age 18 or older.
• Not a full-time student.
• You are not claimed as a dependent on another person’s return.

You can revisit the retirement savings credit section to review your entries. 

1. Log in to your account.
2. Go to Federal Taxes.
3. Go to Deductions and Credits.
4. Scroll down to Retirement and Investments and click show more.
5. Select Retirement Savings Contribution Credit

The Retirement savers  credit is a low income credit and is non refundable.  Frequently a taxpayer is eligible, but because he has no tax liability, he will not actually receive a credit.

Look at form 8880.  Line 10 is your calculated credit. But, line 11 will show the actual amount you get based on your calculated tax liability.   There is also a worksheet showing the calculation for line 11.