What sheet size should I choose?

Standard drywall sheets are 4x8 ft (32 sq ft). For walls with 9–10 ft ceilings, 4x12 ft sheets (48 sq ft) reduce horizontal seams. Choose based on your ceiling height and the seam locations you prefer.

How much waste should I add?

A 10% waste factor is typical for straightforward rectangular rooms. Add 15–20% for rooms with many angles, arched openings, or significant cutouts for outlets and fixtures.

Are doors and windows fully subtracted?

Yes — the calculator subtracts standard door area (21 sq ft) and standard window area (15 sq ft) from the gross wall area before computing sheet count. If your openings are much larger or smaller, adjust the count accordingly.

Does the calculator cover ceilings?

Yes. Select "Walls + Ceiling" or "Ceiling only" and the calculator adds width x length sq ft for the ceiling area to the total.

How are partial sheets counted?

The sheet count is always rounded up to the nearest whole sheet because you must purchase full sheets even when only a partial sheet is needed for a cut.

Can I use metric measurements?

This calculator uses feet and square feet matching North American drywall sizing conventions (4x8 ft, 4x12 ft). For metric projects, convert your room dimensions from meters to feet first (1 m = 3.281 ft).

Drywall Calculator

Name: Drywall Calculator
Availability: InStock
Author: Nham Vu

Calculate how many drywall sheets are needed for walls and ceilings given room dimensions, with waste factor and cost estimate.

Room Dimensions

Room Width (ft)

Room Length (ft)

Ceiling Height (ft)

Doors

~21 sq ft each

Windows

~15 sq ft each

Sheet Size

Waste Allowance (%)

10% is typical; use 15–20% for complex rooms.

Price per Sheet ($) (optional)

Results

Enter dimensions and press Calculate

Summary

Calculate how many drywall sheets are needed for walls and ceilings given room dimensions, with waste factor and cost estimate.

How it works

Enter room width, length, and ceiling height.
Select whether to include walls, ceiling, or both.
Enter the number of doors and windows to subtract their area.
Choose your drywall sheet size (4x8 or 4x12) and set a waste allowance.
Optionally enter the price per sheet for a total cost estimate.
Click Calculate to see the number of sheets required and total cost.

Use cases

Estimating drywall material for a new room addition or basement finish.
Budgeting sheet count and cost before a renovation project.
Planning ceiling drywall separately from wall drywall.
Comparing 4x8 vs 4x12 sheet counts to minimize seams.
Generating a quick material takeoff for a contractor quote.
Calculating waste-adjusted sheet count for odd-shaped rooms.
Determining total job cost when buying drywall in bulk.
Verifying a supplier quote against your own measurements.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu