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Concrete & Wallpaper Quantity Calculator
Work out how much concrete or wallpaper you need. Enter your sizes and get the cubic yards of concrete or the number of wallpaper rolls to buy, with extra for waste.
Choose Concrete or Wallpaper, enter the sizes and press Calculate to see how much to order.
What Is a Concrete and Wallpaper Quantity Calculator?
A concrete and wallpaper quantity calculator helps you buy the right amount of material before you start a job. It is useful for home owners, renters, builders and anyone planning a project. Use the Concrete tab to find the cubic yards or cubic metres of concrete for a slab, patio, path or round pad. Use the Wallpaper tab to find the number of rolls for your walls.
Both tools allow for waste, so you are less likely to run short on the day. They run in your browser and need no sign up.
How to Use This Calculator
- Choose Concrete or Wallpaper at the top of the calculator.
- Choose the units. Use feet, inches and yards, or metres and centimetres.
- For concrete, pick a rectangle or a circle, enter the size and the thickness, and choose the extra for waste.
- For wallpaper, enter the total width of the walls, the wall height, the roll size and the pattern repeat.
- Press Calculate. You get the amount to order and a helpful comparison table.
How Much Concrete Do You Need?
Concrete is sold by volume, so the calculator multiplies the area by the thickness:
- Volume = length x width x thickness. For a circle, the area is 3.1416 x diameter x diameter / 4.
- Cubic yards = volume in cubic feet / 27.
- Order amount = volume x (1 + extra for waste), rounded up.
A bag of 80 lb premix gives about 0.6 cubic feet of concrete. Concrete weighs about 150 lb per cubic foot, or 2,400 kg per cubic metre.
Example: a 10 x 10 ft slab that is 4 inches thick has a volume of 33.3 cubic feet, which is 1.23 cubic yards. With 10% extra you need about 1.36 cubic yards, or about 62 bags of 80 lb premix.
Concrete Needed by Slab Size
The table shows slabs that are 4 inches thick.
| Slab size | Concrete needed | With 10% extra | 80 lb bags with 10% extra |
|---|---|---|---|
| 10 x 10 ft | 1.23 cu yd | 1.36 cu yd | 62 |
| 10 x 12 ft | 1.48 cu yd | 1.63 cu yd | 74 |
| 12 x 12 ft | 1.78 cu yd | 1.96 cu yd | 88 |
| 12 x 20 ft | 2.96 cu yd | 3.26 cu yd | 147 |
| 20 x 20 ft | 4.94 cu yd | 5.43 cu yd | 245 |
| 20 x 30 ft | 7.41 cu yd | 8.15 cu yd | 367 |
How Many Rolls of Wallpaper Do You Need?
Wallpaper is cut in vertical strips, so the calculator counts strips instead of area:
- Strips = total wall width / roll width, rounded up.
- Strip length = wall height + 4 inches (10 cm) for trimming. With a pattern repeat, the length is rounded up to the next full repeat.
- Strips per roll = roll length / strip length, rounded down.
- Rolls needed = strips / strips per roll, rounded up.
Example: a 12 x 12 ft room has 48 ft of wall. With 8 ft walls and a roll that is 20.5 inches wide and 33 ft long, with no pattern repeat, you need about 10 rolls.
Wallpaper Rolls by Room Size
The table shows rolls for rooms with 8 ft walls, a roll of 20.5 inches by 33 ft and no pattern repeat. Doors and windows are not deducted.
| Room size | Wall width | Rolls needed |
|---|---|---|
| 10 x 10 ft | 40 ft | 8 |
| 10 x 12 ft | 44 ft | 9 |
| 12 x 12 ft | 48 ft | 10 |
| 12 x 14 ft | 52 ft | 11 |
| 14 x 16 ft | 60 ft | 12 |
Buying Tips for Concrete and Wallpaper
Concrete
- Order extra. Add 5 to 10% for uneven ground, spills and forms that bow.
- Pick the right thickness. Patios and walkways are often about 4 inches thick. Driveways are often 5 to 6 inches. Heavy loads need more, so check your local building rules.
- Small jobs. For small jobs, bagged premix is easy to handle. For large jobs, ready mix delivered by truck saves time.
- Prepare the base. A compacted gravel base helps the slab last longer.
Wallpaper
- Check the roll size. Roll width and length change between countries and brands.
- Mind the pattern repeat. A large repeat can waste a lot of paper, so you may need more rolls.
- Buy one spare roll. It covers mistakes and later repairs.
- Same batch. Check the batch number on every roll so the colour matches.
Frequently Asked Questions
How many bags of concrete do I need for a 10 x 10 slab?
A 10 x 10 ft slab that is 4 inches thick needs about 33.3 cubic feet. With 10% extra that is about 62 bags of 80 lb premix. Ready mix may be cheaper for a job this size.
How many cubic yards of concrete is a 10 x 10 slab?
A 10 x 10 ft slab at 4 inches thick is about 1.23 cubic yards. With 10% extra, plan to order about 1.36 cubic yards.
How thick should a concrete slab be?
Patios, paths and shed bases are often about 4 inches thick. Driveways are often 5 to 6 inches. Heavy vehicles or poor soil need a thicker slab, so ask a local professional and check local building rules.
How much extra concrete should I order?
Order 5 to 10% extra. It is cheaper than running short, because a second pour can leave a weak joint between old and new concrete.
How many rolls of wallpaper do I need for a 12 x 12 room?
With 8 ft walls, a standard roll of 20.5 inches by 33 ft and no pattern repeat, you need about 10 rolls. A pattern repeat or taller walls can raise this number.
What is a pattern repeat and why does it matter?
The pattern repeat is the distance before the design repeats. Each strip must line up with the next one, so you cut longer strips and lose more paper. The bigger the repeat, the more rolls you may need.
Should I buy extra wallpaper?
Yes. Buy at least one spare roll from the same batch. Colours can differ slightly between batches, and you may need paper later for repairs.
Note: This calculator gives an estimate. Measure carefully and ask your supplier to confirm the final quantity. For structural concrete work, talk to a qualified professional.