How do I estimate how much drywall I'll need?

Is there a formula for estimating how much drywall is required for a job?

• perimeter = 140'
• area = 490sqft

I'm guessing around 45 12x4 sheets, but I would like to confirm my guess before ordering.

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What are the actual dimensions of the walls/ceiling that need to be covered? This math seems wrong. Length = 140' X Width(height) = 3.5'(that's a short room) = 490 sqft. 45 12x4(48sqft) sheets = 2160 sqft. – Tester101 Aug 26 '11 at 20:10
@Tester, I think the area was only for the ceiling, not the area of the walls. – BMitch Aug 26 '11 at 20:15
@BMitch: Maybe... It's Friday, so my brain is not working so good. – Tester101 Aug 26 '11 at 20:29
I may have overestimated a little. 60 sheets of 8x4. docs.google.com/spreadsheet/… – Kevin Aug 30 '11 at 1:17

Add the area of the ceiling by the area of the walls and then factor in some extra for waste. So if you have 8' ceilings, those walls would be 1120 sqft themselves. Add the 490 sqft for the ceiling would give 1610 sqft. Then add in a factor for waste. The less experience you have, and the more angles and corners you have to cut, the more waste you'll have. I think 5% waste is on the low end for our projects, but we have lots of closets, halls, and inexperienced volunteers doing the cutting. That would give you 36-38 sheets of 12x4 (1610 / 48 = almost 34, with 5% waste you get 36, 10% waste gives you 38).

Before you order, since this is a basement, if there's any mold or mildew risk, get mold proof drywall. Also, if you don't have some experienced help, I'd go for the 4x8 sheets. With experience and a lift, it's possible to do 4x8 sheets by yourself, but a 4x12 sheet is often a 3 person job (2 to hold, one to screw). Just realize the 4x8 sheets will require more joints to mud. If you go with 4x8 sheets, since they are 32 sqft each, you'd end up with 54-56 sheets.

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I bought a drywall lift for fixing some water damage on my ceiling. It really took the stress out of hanging 4'x8' sheets by myself, especially since it was the first time I had hung drywall. – Doresoom Aug 26 '11 at 20:24
I love the lifts. They are cheap to rent too, and if you want to get them even cheaper, rent them in the afternoon and return them the next AM for a half day rental fee (that was home depot). That said, others will swear by a simple 2x4 T that they use to prop up one side. – BMitch Aug 26 '11 at 20:27

Addendum to what BMitch said: you want the blue/purple drywall, not the green or white stuff. Use a compatible joint compound and the nonorganic (usually green or yellow) fiberglass mesh tape.

My calculation technique is different. I count by sheet that needs to be hung... I measure out 8' om the wall or ceiling, then measure 4' from that, the. Remind myself that I need to offset the next hang by 4', so if I'm hanging a room that's 9' in one direction, the second row is going to take 2 sheets. I found myself shorting a lot if I used the math method, esp. with rooms that have an odd angle (like a peaked or coffered ceiling). Then add another 10% in sheets, rounding up... More if you have a crew do it and they get paid by how many sheets they hang, aka use.

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