​One of the most expensive mistakes you can make on a drywall installation is ordering the exact square footage of your walls. Unlike lumber, small scraps of drywall cannot easily be pieced together to fill gaps without creating an absolute taping nightmare.

To avoid running short in the middle of a project, professional contractors always apply a waste factor percentage to their raw material orders.

Standard Waste Factor Cheat Sheet

​The amount of extra sheetrock you need to buy depends entirely on the layout and complexity of the room you are remodeling:

10% Waste Factor: Use this for standard rectangular rooms with straight 8-foot ceilings, few windows, and minimal cutouts.

15% Waste Factor: Use this for kitchens, bathrooms, or rooms with multiple doors, windows, alcoves, or electrical built-ins. Every cutout means throwing away a section of the board.

20% Waste Factor: Use this for complex architectural features, cathedral or vaulted ceilings, soffits, and tight hallways where boards must be cut into narrow strips.

Material Rounding Rules

Always remember that drywall is sold in standard panel sizes—most commonly 4×8 sheets (32 square feet per sheet). Once you add your waste percentage to your total square footage, divide by 32 and always round up to the next whole sheet. Having one extra board left over is far cheaper than paying for a second delivery fee or wasting time driving back to the supply yard.

Skip the manual math and get an exact, instant material list using our built-in tool below: