Estimate materials before you buy, and size equipment before you shop. Every calculator shows its formula, a worked example and the assumptions you can change.
- Concrete Calculator: Cubic Yards and Bags for a Slab or Pad
Calculate the concrete volume for a rectangular slab, pad or footing in cubic feet and cubic yards, and the number of bags based on the yield printed on your bag.
- Dripping Faucet Calculator: How Much Water and Money a Drip Wastes
Count the drips, enter your water rate, and estimate how many gallons a leaky faucet or showerhead wastes in a year, based on EPA WaterSense figures.
- Drywall Calculator: How Many Sheets Do I Need?
Estimate drywall sheets for walls and ceilings from room dimensions, openings, sheet size and a waste allowance, with a worked example and buying tips.
- Paint Calculator: How Much Paint Do I Need for a Room?
Estimate gallons of wall paint from your room's wall length, height, doors, windows, number of coats and the coverage printed on your paint can.
- Room AC BTU Calculator: What Size Air Conditioner Do I Need?
Find the right cooling capacity for a window or portable air conditioner based on room size, using the ENERGY STAR sizing chart and its adjustments for sun, occupancy and kitchens.
- Tile Calculator: How Many Tiles and Boxes for a Floor or Wall?
Estimate tiles for a floor, backsplash or shower wall from the area, tile size, grout joint and a waste allowance, and convert the result into boxes.
How to use these calculators
Each calculator runs entirely in your browser; nothing you type is sent anywhere. The fields start with example values so you can see how the result changes, but the most important numbers come from your own project: measure the room, and read coverage or yield from the product label rather than relying on the example. Products differ, and the label is what the manufacturer stands behind.
Why estimates include extra
Real projects waste some material. Drywall sheets are cut around openings, tile is cut at edges and some pieces break, and concrete spills or fills low spots in the base. The waste and extra fields let you set an allowance that fits your job. A simple rectangular room needs less extra than a room with many corners, angled walls or a diagonal tile layout.
When to ask a professional
These tools are for planning and shopping. Structural concrete, large slabs, whole-house heating and cooling sizing, and any work that needs a permit should be planned with a contractor who can measure on site. For central heating and cooling systems, a professional load calculation accounts for insulation, windows and climate in ways a simple area chart cannot.