Determining the weight of a window sash parts is best left to the window pros and experts. However, what you do need is the type of sash, wood or aluminum etc. and the size – we can go from there. Most homes have several sizes of windows and the size, color coding, design of the balance and more. Window balances such as Channel Balances, Spiral Balances, Spring Balances, Tape Balances, Tube Balances should all be correctly ordered as to the size and weight of the window sash. Most are custom made and non-returnable – so we definitely suggest you work with an online pro and don’t hesitate to spend the time necessary for proper ID / Identification and product selections. Few homeowners will know the sash weights. The existing balance size, width, depth, diameter, product markings, BSI markings will all help in proper ordering. Using OEM original builder parts will produce best results. Always replace in sets or pairs.