Drywall & insulation calculators
Drywall and insulation calculators for sheets, mud, batts, and R-value.
Estimate board counts, finishing supplies, studs, insulated area, product coverage, and rough material quantities before buying wall and ceiling materials.
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Quick answers
Drywall sheets by room size
Walls plus ceiling at 8 ft high with 10% waste, no openings subtracted. Mud is 4.5 gal boxes of all-purpose joint compound for three coats.
| Room | Sq ft | 4x8 | 4x12 | Mud |
|---|---|---|---|---|
| 10 x 10 ft bedroom | 420 | 15 | 10 | 2 |
| 12 x 12 ft bedroom | 528 | 19 | 13 | 3 |
| 16 x 20 ft living room | 896 | 31 | 21 | 4 |
| 24 x 24 ft garage | 1,344 | 47 | 31 | 6 |
Quick answers
Batt insulation coverage by R-value
Typical square feet per package of fiberglass batts, and packages for 500 sq ft with 5% waste. DOE guidance: attics R-38 to R-60, walls R-13 to R-21, floors R-25 to R-30. Confirm coverage on the package you buy.
| R-value | Sq ft per package | Packages for 500 sq ft |
|---|---|---|
| R-13 | 88 | 6 |
| R-15 | 88 | 6 |
| R-19 | 75 | 7 |
| R-21 | 67 | 8 |
| R-30 | 88 | 6 |
| R-38 | 64 | 9 |
Method
Wall planning starts with area, then product coverage
Drywall sheets
ceil((wall area + ceiling area) / sheet area)
Finishing supplies
estimate joint compound, tape, and screws from sheet count
Insulation
area / product coverage, adjusted by R-value and material type
Sources
- US Department of Energy insulation guidance — insulation, R-value, and building envelope context
- The Home Depot drywall buying guide — drywall sheet and project planning context
- Lowe's insulation buying guide — insulation types and R-value planning context
Sources checked
Checked against
Sheet, compound, and insulation coverage checked against manufacturer specs and DOE R-value guidance.
How we check our numbersLast updated: October 4, 2026
FAQ
Drywall and insulation calculator questions
Quick answers for sheet counts, finishing supplies, insulation area, and R-value.
How many sheets of drywall do I need for a 12x12 room? + -
A 12 x 12 ft room with 8 ft walls and a ceiling is about 528 sq ft of board. With 10% waste that is 19 sheets of 4x8 or 13 sheets of 4x12, before subtracting doors and windows.
Should I calculate drywall or insulation first? + -
Use drywall when planning sheets, mud, tape, screws, and studs. Use insulation when planning cavity area, R-value, batts, rolls, or blown-in bags.
Do drywall calculators include ceiling area? + -
The drywall calculator can include wall and ceiling area, then converts sheet area into common 4x8 or 4x12 sheet counts.
Is R-value the same as insulation thickness? + -
No. R-value depends on material type and thickness. Use the insulation calculator as a planning estimate and confirm product labels for the exact R-value.