JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Here's a guide on how to calculate fields:
1. Add two Text Boxes you want to calculate.
2. Go to More Fields, type Form Calculation in the search box and drag it to your form.
3. In the Calculation wizard, you can set a formula that adds the value of the 2 fields. Here's a screen animation:
Also, please check this user guide on how to perform calculation.
Hope this helps. Let us know if you need further assistance. Thank you!