Material Cost Estimator by Room Size
Estimate the cost of common materials — flooring, paint, and drywall — based on your room's dimensions and selected material type.
Formulas Used
Floor Area = Length × Width
Flooring Cost = (Floor Area × Waste Multiplier) × Rate per sq ft
Wall Area = 2 × (Length + Width) × Ceiling Height
Net Wall Area = Wall Area − (Doors × 20 sq ft) − (Windows × 15 sq ft)
Total Paint Area = Net Wall Area + Ceiling Area (= Floor Area)
Gallons of Paint = ⌈Total Paint Area ÷ 175⌉ (2-coat coverage: 350 sq ft/gal ÷ 2)
Paint Cost = Gallons × Price per Gallon
Drywall Sheets = ⌈(Net Wall Area + Ceiling Area) × Waste Multiplier ÷ 32⌉
Drywall Cost = Sheets × $15 per sheet
Total Cost = Flooring Cost + Paint Cost + Drywall Cost
Waste Multiplier = 1 + (Waste % ÷ 100)
Assumptions & References
- Standard door opening deduction: 3 ft × 6.8 ft ≈ 20 sq ft per door.
- Standard window deduction: 3 ft × 5 ft = 15 sq ft per window.
- Paint coverage assumes 2 coats at 350 sq ft per gallon per coat → 175 sq ft effective per gallon.
- Drywall sheet size: 4 ft × 8 ft = 32 sq ft; price based on standard ½-inch gypsum board (~$15/sheet, 2024 U.S. average).
- Flooring prices are U.S. national averages for materials only (HomeAdvisor / Fixr, 2024).
- Paint prices reflect interior latex paint per gallon (Consumer Reports / HomeDepot, 2024).
- A 10% waste factor is the industry standard for most flooring and drywall installations.
- Labor, subfloor prep, primer, grout, adhesive, trim, and sales tax are not included.