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.
You may use the DateTime field from Quick Tools for capturing Date of Birth.
We also have Birth date picker that can be added to your JotForm
Please check the following demo form that might help you in achieving your requirement with calculating age in days.
Please feel free to clone this JotForm to your account to see how it works. Hope this information helps. Let us know if you need any further assistance. We will be happy to help.
You might also like to try this form.
It gives an accurate age in years using the Birth Picker.