Construction Calculator
A construction calculator turns job dimensions into material quantities. Enter length, width and depth, choose feet or meters, and get area, cubic feet, cubic yards, bags or tons right away. Results are estimates for ordering and planning, so always confirm with your supplier and add waste before you buy.
Job index: 30 calculators on the way
Each calculator page opens with the working tool and follows with formulas, a worked example and FAQ. Tags without a link are still being built.
- AreaSquare footageSOON
- MaterialGravelSOON
- VolumeCubic feetSOON
- VolumeCubic yardsSOON
- FramingStairsSOON
- LumberBoard feetSOON
- MaterialAsphaltSOON
- VolumePool volumeSOON
- MaterialStoneSOON
- MaterialTopsoilSOON
- FramingRoof pitchSOON
- InteriorDrywallSOON
- ConcreteConcrete bagsSOON
- OutdoorDeckSOON
- InteriorTileSOON
- ToolsFeet-inch mathSOON
- VolumeWater weightSOON
- ConcreteSlab costSOON
- OutdoorFenceSOON
- InteriorWallpaperSOON
- MasonryConcrete blockSOON
- MasonryPaversSOON
- LumberPlywoodSOON
- OutdoorSodSOON
- ElectricalRecessed lightsSOON
- LengthLinear feetSOON
- MasonryBrickSOON
- ExteriorSidingSOON
- InteriorFlooringSOON
- FramingRaftersSOON
How the calculator works
Most material orders come down to one number: volume. Multiply the length, width and depth of the space in the same unit, then convert to the unit the supplier sells in. Concrete, gravel, sand and topsoil are sold by the cubic yard, lumber by the board foot and stairs are laid out from the total rise.
| Quantity | Formula | Example |
|---|---|---|
| Area | length × width | 10 ft × 12 ft = 120 sq ft |
| Volume (cu ft) | area × depth in feet | 120 sq ft × (4 ÷ 12) = 40 cu ft |
| Cubic yards | cu ft ÷ 27 | 40 ÷ 27 ≈ 1.48 cu yd |
| Weight (tons) | cu yd × tons per cu yd | 1.11 × 1.4 ≈ 1.56 tons |
| Board feet | thick in × wide in × length ft ÷ 12 | 2 × 10 × 8 ÷ 12 ≈ 13.3 bd ft |
Worked example: a 10 × 12 ft slab, 4 in thick
- Area: 10 × 12 = 120 sq ft.
- Depth in feet: 4 ÷ 12 = 0.333 ft, so volume = 120 × 0.333 = 40 cu ft.
- Cubic yards: 40 ÷ 27 = 1.48 cu yd. With 10% waste that is about 1.63 cu yd.
- Bags: at about 0.6 cu ft per 80 lb bag, 40 ÷ 0.6 ≈ 67 bags before waste.
Unit conversions you will use
| From | To | Multiply by |
|---|---|---|
| feet | meters | 0.3048 |
| inches | centimeters | 2.54 |
| cubic yards | cubic feet | 27 |
| cubic yards | cubic meters | 0.7646 |
| square yards | square feet | 9 |
Stair layout in plain terms
Divide the total rise (floor to floor) by a comfortable riser height, usually between 7 and 7¾ inches, and round to a whole number of steps. Then divide the total rise by that number to get the exact riser. A stair with n risers has n − 1 treads. For 105 in of rise at about 7.5 in per riser, you need 14 risers and 13 treads. At a 10 in tread depth, the total run is 130 in.
Tips for ordering
- Measure twice and keep every dimension in the same unit before multiplying.
- Slopes, soft ground and forms that bow out all use more material than the flat estimate.
- Ask the supplier about minimum delivery loads and price per half yard.
- Keep the ticket: unused bagged material is easier to return than loose material.
Frequently asked questions
How many cubic feet are in a cubic yard?
One cubic yard equals 27 cubic feet (3 ft × 3 ft × 3 ft), or about 0.7646 cubic meters.
How much extra material should I order?
Many contractors add roughly 5 to 10 percent for waste, spillage and uneven ground. Use the waste field and ask your supplier what they recommend for the material.
How many 80 lb concrete bags make a cubic yard?
An 80 lb bag of ready-mix concrete yields about 0.6 cubic feet, so one cubic yard needs about 45 bags. Check the yield printed on the bag you buy.
How do I convert gravel from cubic yards to tons?
Multiply cubic yards by the material density. Crushed stone and gravel are often quoted around 1.3 to 1.5 tons per cubic yard, but the exact figure depends on the stone, moisture and size. Ask the yard for theirs.
What stair rise and run are allowed?
The International Residential Code limits residential risers to 7¾ in and requires treads of at least 10 in. Local codes can differ, so check yours before you cut stringers.
Is this calculator structural advice?
No. It estimates quantities for ordering and planning. It does not size beams, footings or reinforcement. Ask a licensed engineer or your building department for load-bearing work.
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