Variation in price in invoice

Hi,
I have a problem in invoice making that we always quote/get the price of 40kg of any item we purchase or sell but we sell/purchase items in packing of different variations e.g. 50KG bag or 25 KG bag. I am entering the price in invoices by calculating manually in calculator. I want to ask that if there is a way so I just enter the price of 40KG and weight of package and create the invoice according to it.

if you create the inventory as 1KG and set a sale price for it, then you can sell it as 50KG or 25KG by entering the unit price of 1KG. Manager will automatically calculate the total amount.

thanks for your reply, but problem is that we sell and make invoice according to bags quantity not according to weight. sale price also varies in different customers.

You can create separate inventory items for raw materials and finished goods, you would have to use production orders to convert between them.