Help with a math problem: converting square metre price formula

详细信息

We're looking for someone who can help develop a workable solution to what is essentially a math problem.
We sell custom outdoor furniture covers. Our website allows customers to enter their dimensions so we can calculate the number of square metres of material. The retail price is then calculated based on the quantity of square metres of material * price per square metre. This system relies on three inputs (width x depth x height), as long as we have this information then we can calculate the price.
We are now looking at selling some of these products on Amazon. Whilst Amazon does support custom products, their customisation options are extremely basic. Their system is really designed for sellers who want to allow customers to add logos to mugs or tshirts (1 logo = £5, 2 logos £9 and so on). There is no way we can set up three inputs as described above, and then use a formula to calculate square meterage of fabric * price per square metre. No way at all.
So what does Amazon allow us to do?We can set up drop-down menus with predefined measurements (e.g. 75cm, 76cm, 77cm and so on) and we can assign a price to each of those measurements. In that way, we can have 3 drop-down menus, each with a full list of measurements and prices.
The math problem is this:Is there a way we can rework our current price per square metre cost calculation system so that we can make it work within the confines of Amazon's drop-down menus? A successful outcome would mean that the customer is able to select 3 measurements from the 3 Amazon drop-down menus and see a total price that is the same or similar to the output of our current website cost calculation system (based on square meterage of material).
I explain the problem in more detail via the below Loom video.
https://www.loom.com/share/c29c412b8d254760bb05ffeb3d9b5312?sid=1bcadeb4-a943-4a05-85f1-d8514ba84fc6