set price for size, defined for customer

Hi!
How i can set the Price for size, but the size defined for the customer?

For example.

Product Windows.
Price for square meter $400
the customer put the size, 2x2.50 square meter.
and automatic calculate the Price, result $2000

But always automatic.

I wait for some comment
Thanks!

This is not available out of the box. You can vote for the workitem

voted Eduardo!

Maybe any developer see this issue and add this option.
Is a good method to open the posibility to sell other products.

Much people need this. Not all people sell standard products.

Thanks!
Acord.

Id like this option too.

We have products that need to be calculated per square meter before printing. There is no way we can predefine every single product with a square m2 price. Customers can have different size requests.