Calculation Results
Choose a calculation mode
Saved calculation history
Formula used
Board area: width × length. Net area removes openings. Purchase boards include layers and waste.
Plaster volume: area × thickness. Dry mass uses coverage or density. Bag count rounds upward.
Agricultural gypsum: field area × application rate. Purity and moisture increase commercial material needs.
How to use this calculator
- Choose boards, plaster, or agricultural gypsum.
- Enter measurements using the available units.
- Add waste, purity, costs, and accessory rates.
- Select Calculate Gypsum to view detailed results.
- Copy, print, or export the completed estimate.
Example data
| Mode | Example input | Typical result |
|---|---|---|
| Boards | 40 m², 12.5 mm, 10% waste | Board count, accessories, weight, and cost |
| Plaster | 100 m², 12 mm, 1.2 kg/m²/mm | Dry mass, water, bags, volume, and cost |
| Agriculture | 1 hectare, 1 tonne/ha, 85% purity | Adjusted mass, bags, loads, and cost |
Common gypsum board sizes
| Nominal size | Area | Common use |
|---|---|---|
| 1200 × 2400 mm | 2.88 m² | General walls and ceilings |
| 1200 × 2700 mm | 3.24 m² | Taller rooms |
| 1200 × 3000 mm | 3.60 m² | Reduced horizontal joints |
| 4 × 8 ft | 32 ft² | Standard imperial projects |
| 4 × 12 ft | 48 ft² | Large walls and fewer joints |
Waste allowance guidance
- Use 5% for simple, open rectangular rooms.
- Use 10% for most residential installations.
- Use 15% for many corners or openings.
- Use 20% for complex layouts and small sections.
Frequently asked questions
Does the board calculation deduct windows and doors?
Yes. Add every opening separately. The calculator deducts their combined area.
Can I calculate ceilings and walls together?
Yes. Add multiple surface sections. Label each section for easier review.
How is board waste calculated?
Waste applies after layers are included. The final board count rounds upward.
Does orientation change the material area?
Area stays unchanged. Orientation mainly affects joints, cuts, and installation planning.
How accurate is the screw estimate?
It uses your screws-per-board rate. Local fixing standards may require adjustments.
Can plaster be calculated using density?
Yes. Select dry bulk density. Enter the supplier’s stated density value.
Why does agricultural purity increase the quantity?
Lower purity supplies less active gypsum. More commercial product becomes necessary.
How is moisture handled?
Moisture adds non-dry weight. The calculator adjusts the purchased mass accordingly.
Are cost estimates final quotations?
No. They are planning estimates. Confirm prices, taxes, labour, and delivery locally.
Can results be saved?
Recent results are stored locally. Clearing browser storage removes saved history.