How do I add sub-products in the Inventory?

I sell products with different colors each item that are in a dropdown menu. Is there a way to count my inventory of each color?

I suggest you to try the 'Quantity Gift Registry' widget.

link: http://widgets.jotform.com/widget/quantity_gift_registry

Here is a demo form https://form.jotform.com/193471927725973

This widget will allow you to have inventory management to sell products with different colors in your form. You can set the initial inventory and then it will diminish according to the quantity being sold.

Please let us know how it goes.

Regards.

Tried that, but they are like radio buttons. Can i use it in a dropdown?
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Unfortunately, the dropdown you mentioned isn't possible on the Gift Registry Widget. You might want to consider the 'Inventory Widget' where it shows a dropdown quantity but it may not fulfill your mentioned requirements. Give it a try and see if that suits your needs.

Let us know if you need any additonal assistance.

Tried that too but the dropdown is for quantity. What I am trying to do is
my color option in dropdown then with inventory of each color. Like gift
registry but in a dropdown.
...

Do you want something like this:

https://form.jotform.com/193483103689971

If yes, then you may use the Purchase Order widget.

Guide: https://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form

Let us know if you have further questions.

Thanks.

No, not like that.
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I'm sorry, I'm not sure I understand what you mean by color option in the dropdown then with the inventory of each color.  Can you help us by giving us more details like your product list and how do you want your product to be listed, please, so we can assist you better?

I suggest you to test our Dynamic Dropdowns Widget: https://www.jotform.com/widgets/dynamic-dropdowns, I think might be this kind of product structure you are referring to. However, if true, then it might not be possible to achieve the requirements. 

We request you to share us some information regarding the product catalog so that we can help you out in finding any workaround and creating the desirable form.

We will be waiting for your response.