Maximizing Your Forms: Calculating Form Fields

Written by Chris Lucas on November 1, 2007

Posted in Form Hacks

Not every form is going to be a simple contact form or newsletter sign up. Formstack can be used to create all sorts of complex forms, like ones that require you to perform calculations, like an order or event registration form.

Using the calculating form fields is a quick and easy way to create a seamless process for your website visitors. By calculating the fields and using all the tools within Formstack you can ensure that your forms create a great user experience.

To get started simply login to your account and start creating your form. For a quick demo on getting started watch our introduction to Formstack.

For this instance we have created an event registration form. We want to register participants for a dinner where each seat costs $100. First create a “Number Attending” field, we use a drop down, but you can use another type if you wish.


Then create a read only “Cost per Person” field. In the default value put in $100.


Next, add a “Total Cost” field, you will also want to make this a read only field. Below the “Default Value” box you will see a “Use Calculation” link. Click the link and you will be able set your formula. You can choose to add, subtract, or multiply certain fields. For this situation use the “Number Attending” field x “Cost per Person” field.


Finally, when users go to register for your event they will be able to choose the number of attendees and the form will calculate the final cost for them. The form will look like this:


Remember if you are creating order forms or collecting valuable customer information you need to use the security features within Formstack. You can learn more about them here.

Tell us how you use the calculating fields in the comment section below!