Sheetrock Calculator

Sheetrock & Drywall Estimator

function calculateDrywall() { var length = parseFloat(document.getElementById('roomLength').value) || 0; var width = parseFloat(document.getElementById('roomWidth').value) || 0; var height = parseFloat(document.getElementById('wallHeight').value) || 0; var sheetSqFt = parseFloat(document.getElementById('sheetSize').value); var ceiling = document.getElementById('includeCeiling').checked; var windows = parseInt(document.getElementById('windowCount').value) || 0; var doors = parseInt(document.getElementById('doorCount').value) || 0; // Calculate wall surface area var wallPerimeter = (2 * length) + (2 * width); var wallArea = wallPerimeter * height; // Calculate ceiling surface area var ceilingArea = ceiling ? (length * width) : 0; // Deductions (Average door 21 sq ft, average window 12 sq ft) var deductions = (windows * 12) + (doors * 21); // Total area minus openings var netArea = (wallArea + ceilingArea) – deductions; if (netArea < 0) netArea = 0; // Apply 10% waste factor var areaWithWaste = netArea * 1.10; // Materials calculations var sheets = Math.ceil(areaWithWaste / sheetSqFt); // Joint compound (Approx 0.05 gallons per sq ft of board) var compound = (areaWithWaste * 0.052).toFixed(1); // Drywall tape (Approx 0.15 feet per sq ft of board) var tape = Math.ceil(areaWithWaste * 0.14); // Display results document.getElementById('results').style.display = 'block'; document.getElementById('sheetsNeeded').innerText = sheets; document.getElementById('totalSqFt').innerText = Math.round(netArea); document.getElementById('compoundNeeded').innerText = compound + " Gal"; document.getElementById('tapeNeeded').innerText = tape + " Ft"; }

How to Estimate Sheetrock Projects

Estimating sheetrock (or drywall) involves calculating the total surface area of all walls and ceilings, then dividing by the square footage of the sheet size you intend to use. Most residential construction uses 4'x8′ sheets, but 4'x10′ or 4'x12′ options are often used for taller ceilings or to minimize the number of joints.

The Calculation Formula

The standard math for a rectangular room is as follows:

• Wall Area: (Length + Width) x 2 x Height
• Ceiling Area: Length x Width
• Deductions: Subtract roughly 15-20 sq ft for every door and 12-15 sq ft for every window.
• Waste Factor: Always add 10% to your final area to account for cuts, breakage, and waste.

Common Sheet Sizes

Choosing the right sheet size can save you hours of sanding and finishing:

• 4 x 8 Feet (32 sq ft): The industry standard. Easy to transport and carry, but creates more vertical seams.
• 4 x 10 Feet (40 sq ft): Ideal for 9-foot ceilings or long walls to reduce joint count.
• 4 x 12 Feet (48 sq ft): Professional choice for long stretches, though very heavy and difficult to move in tight spaces.

Realistic Example

If you are finishing a standard 12′ x 12′ bedroom with 8-foot ceilings and including the ceiling:

• Walls: (12 + 12) x 2 x 8 = 384 sq ft.
• Ceiling: 12 x 12 = 144 sq ft.
• Gross Total: 528 sq ft.
• With 10% Waste: 580.8 sq ft.
• Sheets (4×8): 580.8 / 32 = 18.15. You would order 19 sheets.

Don't Forget the Finishing Materials

A sheetrock job isn't finished once the boards are up. You will also need:

• Joint Compound (Mud): Approximately 0.05 gallons per square foot of drywall.
• Joint Tape: Approximately 0.15 feet of tape for every square foot of wall space.
• Screws: Roughly 1 pound of 1-1/4″ drywall screws for every 500 square feet of board.