Checked the box for maximize SEP IRA contribution and got a really large number. Is there a way to see how it was calculated?

[ThomasM125]

You can see the Sep IRA calculation in the Keogh, SEP and SIMPLE Contribution Worksheet in TurboTax. If you are working online in TurboTax, you can see this worksheet after you pay for your TurboTax program. If you are using the desktop version of TurboTax, you can use the Forms option to see the worksheet. 

[dmertz]

Is more than 1/5 of your net profit from self-employment, it likely means that you marked the Maximize box for an individual 401(k) plan.  You'll be able to see that on the worksheet.