When you enter the 1098, the program will ask if the loan was ever a HELC and if so, how much cash was taken out. 

The program can make the calculation with that information. 

It wasn't a HELC ever... Just a straight cash-out refi so we got a wire into our bank when the new mortgage closed, which we used to pay off debt. So do I need to calculate that percentage based on how much cash we took out when we refinanced?

No, you do not need to calculate the percentage of your mortgage interest that is deductible. As KrisD15 said above, TurboTax will calculate this for you based on your answers to the questions. Please follow these steps:

1. Enter the full amount of your mortgage interest and the other information as it is reported on your Form 1098
2. When you get to the question "Is this loan a home equity line of credit or a loan you've ever refinanced," click on Yes
3. Click on "Yes" to the question "Have you ever pulled cash out from this loan when refinancing it?"
4. Then click on "No" to the question "Have you used the money from this loan exclusively on this home?"
5. Click on  "Help me figure this out" to the question "Let's see how much interest you can deduct this year" and carefully answer the remaining questions

Please refer to this TurboTax Article for more information.

@oddvision

Where do I submit the refi info?

You enter your refi information in the Home mortgage section under Deductions & Credits.

Follow the instructions above to provide the necessary details of your loan. 

If you are having trouble finding the Home mortgage section, use the search box in the upper right corner to search for "1098", then click Go to 1098.