How much drywall mud you need is about 10 gallons, or 140 pounds, for every 1,000 square feet of board. A 12 by 16 room with an 8 foot ceiling has 640 square feet of board once you count the ceiling, so it takes roughly six and a half gallons, or 90 pounds. That is more than most people expect, and it is the single most underestimated order on a drywall job.
Two manufacturers, two units, one answer
USG puts the coverage of Sheetrock all purpose joint compound at approximately 10 gallons per 1,000 square feet of gypsum panels. National Gypsum estimates 140 pounds of ready mix per 1,000 square feet for its ProForm range.
Those look like different numbers until you convert. Ready mixed compound runs a little under 14 pounds a gallon, so 140 pounds is a shade over 10 gallons. Two companies, two units, and the same figure. That is about as close to a settled number as estimating gets.
Joint compound for three coats
board area \u00f7 1,000 \u00d7 10 gallons
Board area, not floor area \u00b7 or multiply by 140 for pounds \u00b7 about 4.5 pounds, a third of a gallon, per 4 by 8 sheet
How much drywall mud you need scales off the board, not the floor
This is where the estimate usually goes wrong. A 12 by 16 room is 192 square feet of floor and 640 square feet of board: 448 on the walls at an 8 foot ceiling, plus 192 overhead. Work the compound off the floor area and you order less than a third of what you need.
The ceiling is the part people forget, and it is also the part that takes the most compound per square foot, because it is where the butt joints land and butt joints need the widest feathering.
Three coats is why it is so much
Ten gallons sounds absurd for a couple of rooms until you count what the compound actually has to do. Every joint gets a bedding coat with tape in it, a fill coat and a finish coat. Every screw head gets the same three passes. Every inside corner gets two sides done separately.
And the compound shrinks as it dries, which is the whole reason there are three coats rather than one. A thick single pass cracks and sinks. Three thin ones, each wider than the last, is what makes a joint disappear under paint.
Sanding takes some of it back off again, and none of that is recoverable. The 10 gallon figure already assumes all of this, which is why it is a coverage rate rather than a volume of finished joint.
Tape comes with it
National Gypsum puts joint tape at 350 feet per 1,000 square feet of board, so that same 12 by 16 room takes about 225 feet. Tape is sold in 250 and 500 foot rolls, so one roll covers the room with a little spare.
It is cheap and running out mid joint is miserable, so this is not the line to trim.
Setting compound is a different order
Quick setting compound, the powder you mix and that hardens chemically rather than by drying, is estimated separately. National Gypsum puts it at 55 pounds per 1,000 square feet, well under half the ready mix figure, because it is normally used for the bedding coat and the fill while ready mix does the finish.
It shrinks less and lets you do more than one coat in a day, which is why it gets used on the coats that have to be thick. It also goes off on a timer, so mix what you can use.
What to actually buy
USG sells all purpose compound in a 4.5 gallon pail, a 4.5 gallon carton and a 3.5 gallon carton. For the 12 by 16 room at six and a half gallons, that is two pails, or one pail and one of the smaller cartons.
Round up rather than down. Compound keeps in a sealed pail for months, a half finished wall does not keep at all, and an all purpose compound will do every coat if you would rather carry one product than three.
Get the board area first
Frequently asked
About 10 gallons or 140 pounds per 1,000 square feet of board. USG rates Sheetrock all purpose compound at approximately 10 gallons per 1,000 square feet and National Gypsum estimates 140 pounds of ready mix for the same area, which converts to just over 10 gallons. A 12 by 16 room with an 8 foot ceiling is 640 square feet of board, so about six and a half gallons.
A 4 by 8 sheet is 32 square feet, so at 10 gallons per 1,000 square feet that is about a third of a gallon, or roughly four and a half pounds, per sheet for three coats.
Divide the gallons by the pail size. USG sells all purpose compound in 4.5 gallon pails and cartons and 3.5 gallon cartons, so a 640 square foot room at six and a half gallons takes two pails, or one pail and one smaller carton. Sealed compound keeps for months, so round up.
National Gypsum estimates 350 feet of joint tape per 1,000 square feet of board, so a 12 by 16 room takes about 225 feet. Tape comes in 250 and 500 foot rolls, so one roll covers that room with some to spare.
No, and it is estimated separately. Setting or quick set compound is a powder that hardens chemically rather than by drying, shrinks less and lets you do more than one coat a day. National Gypsum puts it at 55 pounds per 1,000 square feet, because it is usually used for the bedding and fill coats while ready mix does the finish.