Drywall Mud Calculator

Drywall mud is joint compound, the paste that fills seams, screw dimples and corners between boards. Ready-mixed compound is measured in gallons and sold in pails, and paper joint tape is sold in rolls measured in feet. The calculator scales the maker's typical coverage for both products to your area, then rounds up to whole pails and rolls.

How to use this calculator

1. Work out the area of the drywall in square feet. Multiply each wall's length by its height and add the ceiling. The drywall calculator works out the wall and ceiling areas for a room.
2. Enter that total in the drywall area box. Use square feet, not a count of sheets, because sheet lengths vary.
3. Read the gallons of compound and the feet of tape. Both come from the maker's typical coverage for a standard finish, so treat them as a starting point rather than a guarantee.
4. Round up to whole pails and rolls, which the Buy section does for you. Compound left open in a pail starts to skin over, so it is better to keep a spare pail than to stop mid-job for another.
5. Check the coverage printed on the label of the product you buy. A different brand or a heavier finish changes how much you need, so adjust the order by hand when the label differs.

Worked examples

Ready-mixed or setting-type?

Ready-mixed compound comes premixed in a pail. You stir it and spread it, and it stays workable for as long as the lid stays on.

Setting-type compound comes as a powder in bags. You mix it with water, and it hardens through a chemical reaction instead of drying. That suits deep gaps and repairs, but it is not sold by the pail, so the pail count applies to ready-mixed compound only.

How the calculation works

The calculator scales each maker rate to the area you enter. The compound rate is 10 gallons per 1,000 sq ft, and the tape rate is 370 ft per 1,000 sq ft. A smaller area gets a proportionally smaller amount of both.

Then the calculator rounds up. Ready-mixed compound is commonly sold in pails of 4.5 gallons, and a popular roll of paper tape is 250 ft. The calculator adds no separate allowance for waste, so for a rough wall or a lot of cutting, add a margin to the order by hand.

This calculator covers the mud and tape only. If the finished walls will be papered instead of painted, size the paper with the wallpaper calculator, which needs the room size and wall height rather than a total area.

What changes the amount

The finish level changes how much compound goes on the wall. A basic taped joint that will be covered by texture needs less than a wall skim-coated from edge to edge. The number of coats, and how thickly each one goes on, change the total as well, and the rate above assumes a standard finish.

Corners take extra work. Inside corners, outside corners and the corner bead along them need more compound than a flat run of wall. Rough or patched surfaces also need more, and a finisher who scrapes off a lot of compound will use more than someone who works lightly.

Mistakes to avoid

• Leaving out the ceiling. A flat ceiling is as large as the floor below it, so counting only the walls leaves out a big share of the order.
• Mixing more setting-type powder than you can spread. It hardens chemically, so the unused mix is wasted rather than kept for later.
• Ordering compound without tape. Tape is a separate product with its own rate, so both the pail line and the roll line belong on the order.

Types of joint compound: all-purpose, lightweight and topping

All-purpose compound is the common choice for taping and finishing, and USG rates it at 10 gallons per 1,000 sq ft. Its lightweight compound is rated at 9.4 gallons per 1,000 sq ft, ultralightweight at 9 to 10 gallons per 1,000 sq ft, and topping at 10 to 12 gallons per 1,000 sq ft. Rates differ by brand, so check your product's label.

Common questions