WooCommerce update qty box using AJAX for tiling website

I am working on a WordPress website where I need the functionality of calculating tile boxes using the area mentioned by the buyer. I have achieved the calculation functionality to add the boxes in the cart but I want an additional functionality where, when the user tries to input the value in the qty required box, it should be multiplied with the area covered by one box and should be updated in the input box only. I want the same functionality both on the product page as well as the cart page. If you want to understand the question in a better way, please have a look at this product of the website ([login to view URL]), I want the exact same functionality in my website. Need a custom code that can be added to the website or needs a custom plugin idea to make it work. But the value is not automatically changed in the input box only! Even I want to check it by AJAX, so when the user is entering the qty more than stock, it should check it within 3 seconds and reset the input box value to the default by showing an error. You can try putting "500" as sqm required box in the link I have mentioned by which you can get the idea of what kind of functionality I need in my website.