...To generate accurate quotes, the form needs to perform calculations based on user inputs, such as quantity, product options, and prices. This is where the need for calculations in Contact Form 7 becomes evident.
By introducing calculations, you can provide users with real-time feedback, automated calculations, and tailored results. This can save time, reduce errors, and create a more user-friendly experience, all of which contribute to higher user satisfaction and potentially improved conversions.
https://wordpress.org/plugins/calculation-for-contact-form-7/