This feature is part of the Visforms Subscription and not available in the free Visforms version..
Custom Field Types- Field Types with special functionalities
The Visforms Subscription adds field types that can perform special tasks to Visforms. The first custom field type we have created is the field type "calculation", because it was requested many times.
The field type calculation allows you to directly enter mathematical formulas. The formula can consist of numbers, math operators (plus, minus, multiply, divide) and math functions (like squareroot, absolut value ...) and combine them with current user inputs. The result will be calculated dynamically according to the current user inputs.
This field type enables you, for example, to create an individual order form using all the flexiblity of Visforms to add exactly those fields and texts to the form which you need.
Our demo form can give you a perspective of what can be done with this extension. How to set up such a form is discribed in the Step by Step instruction in this documentation.