onlinecalculator.me

Free online drywall calculator

Drywall takeoffs count sheets for all four walls and the ceiling, then add consumables. Enter your room dimensions to get sheets needed plus joint compound, tape, and screw.

About this calculator

How to use

  1. Enter room length, width, and ceiling height in feet.
  2. Enter the number of doors and windows.
  3. Set a waste factor — 10% is standard.
  4. Read off sheets needed and consumables (mud, tape, screws).

Formulas

wall area  = 2 × (length + width) × height − doors × 21 − windows × 15
ceiling    = length × width
total area = wall area + ceiling

sheet area = sheet width × sheet height   (default 4 × 8 = 32 sq ft)
sheets     = ceil(total area / sheet area × (1 + waste% / 100))

mud (gal)  = ceil(total area × 0.053)
tape rolls = ceil(total area / 500)
screws     = ceil(total area / 500) lb

Worked example

Room 12 ft × 10 ft, 8 ft ceiling, 1 door, 2 windows, 10% waste:

wall area  = 2 × (12 + 10) × 8 − 21 − 30  = 301 ft²
ceiling    = 12 × 10                        = 120 ft²
total      = 301 + 120                      = 421 ft²

sheets     = ceil(421 / 32 × 1.10)         = ceil(14.47) = 15 sheets
mud        = ceil(421 × 0.053)             = ceil(22.3)  = 23 gallons
tape       = ceil(421 / 500)               = 1 roll
screws     = ceil(421 / 500)               = 1 lb

Notes

  • Pre-mixed joint compound is heavier than powdered; powdered is easier to transport and shrinks less.
  • Count 5-gallon buckets rather than gallons when ordering pre-mixed — contractors typically buy in 4.5-gallon buckets.
  • Mesh tape is faster to apply but weaker than paper tape. Use paper tape over butt joints and seams that will flex.
  • Always prime fresh drywall before painting — unprimed paper face soaks up the first coat unevenly.

Frequently asked

How do I calculate how many sheets of drywall I need?
Find the total square footage of walls and ceiling, subtract door and window openings, apply a waste factor, then divide by the sheet area (32 sq ft for 4×8). Round up to whole sheets.
How much joint compound do I need per square foot of drywall?
A common estimate is one gallon of joint compound per 19 square feet of drywall (or about 0.053 gallons per sq ft). This covers three coats — tape, butt, and finish — for a smooth wall.
What waste factor should I use for drywall?
A 10% waste factor handles typical cuts, odd-shaped rooms, and mistakes. Go up to 15% for rooms with many angles, arched openings, or complex soffits.
Should I use 4×8 or 4×12 drywall sheets?
4×8 sheets are standard and easiest to handle solo. 4×12 sheets cover more area per sheet and reduce the number of butt joints, which makes finishing easier — but they require two people to hang.
How much tape do I need?
A rough rule of thumb is one roll (500 ft) of paper or mesh tape per 500 square feet of drywall. The calculator uses this ratio.
How do I share my drywall calculation?
Click Share for the page link, or Share with my numbers to encode your room dimensions in the URL.

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